Birthstones

Birthstones–special stones associated with each month of the year–are fun. But they also have a place in history, in mythology, and in science.

The first association of a special gem with each month was recorded in the Bible, in Exodus 28 and 39. An original breastplate of the High Priest of the Hebrews was said to be made by Moses in 1250 BC, according to instructions he received during 40 days in the mountains. The twelve gems in the breastplate were later linked with the signs of the zodiac, and later still associated with the months in the year. The following describes the High Priest’s breastplate:

“It was square–a span [22 centimeters] long and a span wide–and folded double. Then they mounted four rows of precious stones on it. In the first row there was a ruby, a topaz and a beryl; in the second row a turquoise, a Sapphire and an emerald; in the third row a jacinth, an agate and an ; in the fourth row a chrysolite, an onyx and a jasper. They were mounted in gold filigree settings. There were twelve stones, one for each of the names of the sons of Israel, each engraved like a seal with the name of one of the twelve tribes.” (Old Testament, New International Version, Exodus, Chpt. 39, vs. 9–14)

The precise identification of some of these precious stones is uncertain. For example, if you turn to the same passage in the Revised Standard Version of Exodus, you’ll find that diamonds, sardius, and carbuncle [another name for garnet] are also included in the list of twelve biblically significant gemstones. Also, keep in mind that aquamarines and emeralds are forms of beryl; sardonyx is a form of onyx; and jacinth and chrysolite are also known as zircon and peridot, respectively.

Unless you’re a geologist, the terminology of birthstones may be a bit confusing. So here’s a quick primer on birthstone terms.

What’s the difference between rocks, minerals, and gems? A mineral is made of inorganic materials (substances that were never alive), whose atoms are arranged in a regular pattern, or crystal. Rocks are made up of one or more minerals. Most people also include clay, sand and limestones in the rock category.

Gems are a special subgroup of highly prized minerals. Gems are usually clearer, rarer, and more beautiful than other minerals. Color, luster and hardness are also important qualities that can set gems apart from other minerals. But there’s no hard and fast rule as to which minerals cut it as gems and which don’t. It’s mostly a matter of custom.

What’s the difference between precious and semi–precious gems? Most gems can be divided into precious and semi–precious. Only the most rare and expensive gems are classified as precious. Diamonds, emeralds, rubies, pearls, and sapphires are all considered precious gems. Most remaining gems–such as varieties of quartz (including amethyst, opal, and bloodstone)–are semiprecious.

Now you’re ready to read the special story of your birthstone.

January – Garnet

January’s birthstone is the garnet. Ancient warriors believed that garnets brought victory. The Crusaders used them as protection against wounds and accidents during their journeys. In contrast, Asiatic warriors believed that glowing garnets, used as bullets, inflicted more severe wounds. In 1892, during hostilities on the Kashmir frontier, the Hanza tribesmen fired on British soldiers with garnet bullets, believing them to be more effective than lead bullets.

The name “garnet” is derived from the Latin “granatum” meaning “pomegranate” because the crystals resemble the red color and seed–like form of this fruit. Most people think of the garnet as a red gemstone, but in fact, it exists in all kinds of colors, such as black, many shades of red and green, or even colorless. The garnet’s variety of colors comes from metals such as manganese, iron, calcium, and aluminum. Some varieties even contain mineral fibers that produce the illusion of a four– or six–rayed star within the stone. Green garnets are most highly prized but are very rare. Emerald green and colorless stones are highly valued, followed by pure red garnets.

Garnets are commonly found as small pebbles in streams, where the igneous and metamorphic rocks that contain them have weathered away. They’re found in many places around the world, including North and South America, Australia, India, Asia and Spain.

In the former Czechoslovakia, evidence of garnet jewelry dating to the Bronze age was found–garnet necklaces were discovered in the graves of ancient lake dwellers. Garnet jewelry has also been discovered dating back to 3100 B.C. in Egypt, 2300 B.C. in Sumeria, and 2000–1000 B.C. in Sweden. Garnets were treasured in 3rd and 4th century Greece, and continued in popularity during Roman times. Across the Atlantic, Pre–Columbian Aztec and Native Americans also used garnets in their ornaments.

As with many precious stones, garnets were once believed to hold medicinal powers. In Medieval times, it protected its wearer against poisons, wounds and bad dreams, and cured depression. Red garnets relieved fever, hemorrhages and inflammatory diseases. To modern users, the garnet symbolizes a light heart, loyalty and enduring affections.

February – Amethyst

February’s birthstone is the amethyst. It’s said that the signet ring worn by Cleopatra was an amethyst, engraved with the figure of Mithras, a Persian diety symbolizing the Divine Idea, Source of Light and Life. It is also said to be the stone of Saint Valentine, who wore an amethyst engraved with the figure of his assistant, Cupid. Saint Valentine’s Day is still observed in February.

Amethysts contain the second most abundant mineral found in Earth’s crust–quartz. Quartz is often found lining the insides of geodes. So it’s no wonder that geodes sometimes contain amethysts too. Like quartz, amethysts are a transparent form of silicon dioxide (SiO2). An amethyst’s color can range from a faint mauve to a rich purple. It’s not clear why they’re purple. Some scientists believe the purple color arises from the amethysts’ iron oxide content, while others attribute the color to manganese or hydrocarbons.

Amethysts are very sensitive to heat. When heated to 400 or 500 degrees Celsius, an amethyst’s color changes to a brownish–yellow or red. Under some circumstances, the stones can turn green when heated. Heat may even transform an amethyst into a naturally–rare mineral called citrine. And even without heating, the violet color of an amethyst may fade over time.

Commercial sources of amethyst are Brazil and Uruguay; while in the US, most amethyst is found in Arizona and North Carolina.

The amethyst has a rich history of lore and legend. It can be traced back as far as 25,000 years ago in France, where it was used as a decorative stone by prehistoric humans. It has also been found among the remains of Neolithic man.

The word amethyst comes from the Greek word “amethystos” meaning “not drunk”, and was believed to prevent its wearers from intoxication. The following is a story from Greco–Roman mythology as quoted from “Birthstones” by Willard Heaps:

“Bacchus, the god of wine in classical mythology, was offended by Diana the huntress. Determined on revenge, he declared that the first person he met as he went through the forest would be eaten by his tigers. As it happened, the first person to cross his path was the beautiful maiden Amethyst on her way to worship at the shrine of Diana. In terror, she called upon the goddess to save her, and before his eyes, Bacchus observed the maiden changed to a pure white, sparkling image of stone. Realizing his guilt and repenting his cruelty, Bacchus poured grape wine over her, thus giving the stone the exquisite violet hue of the amethyst. The carryover to nonintoxication was quite logical, and in ancient Rome, amethyst cups were used for wine so drinkers would have no fear of overindulgence.”

The early Egyptians believed that the amethyst possessed good powers, and placed the stones in the tombs of pharoahs. During the Middle Ages, it was used as medication, believed to dispel sleep, sharpen intellect, and protect the wearer from sorcery. It was also believed to bring victory in battle. In Arabian mythology, the amethyst was supposed to protect the wearer from bad dreams and gout. The amethyst was also the stone of royalty, representing power.

March – Aquamarine & Bloodstone

March has two birthstones–aquamarine and bloodstone. The name aquamarine was derived by the Romans, “aqua” meaning water and “mare” meaning sea, because it looked like sea water. Aquamarines were believed to have originated from the jewel caskets of sirens, washed ashore from the depths of the sea. They were considered sacred to Neptune, god of the sea. This association with the sea made it the sailors’ gem, promising prosperous and safe voyages as well as protection against perils and monsters of the sea. Its first documented use was by the Greeks between 480–300 BC. They wore aquamarine amulets engraved with the god Poseidon on a chariot.

Aquamarines vary in color from deep blue to blue–green of different intensities, caused by traces of iron. Naturally occurring deep blue stones are the most prized because they are rare and expensive. However, yellow beryl stones can be heated to change them to blue aquamarines.

The aquamarine–also called the “poor man’s diamond”–is a form of the mineral beryl that also includes other gemstones such as the emerald, morganite and heliodor. Beryl consists of four elements: beryllium, aluminum, silicon and oxygen. Beryl occurs as free, six–sided crystals in rock veins unaffected by shock and weathering that otherwise destroys gem deposits. It is a relatively hard gem, ranking after the diamond, sapphire, ruby, alexandrite and topaz.

The best commercial source of aquamarines is Brazil. High quality stones are also found in Colombia, the Ural Mountains of Russia, the island of Malagasy, and India. In the United States, Colorado, Maine and North Carolina are the best sources.

Beginning in the Roman period, the aquamarine was believed to possess medicinal and healing powers, curing ailments of the stomach, liver, jaws and throat. During the Middle Ages, it was believed to be an effective antidote against poison. Aquamarines were thought to be the source of power for soothsayers, who called it the “magic mirror”, and used it for telling fortunes and answering questions about the future. It is said that Emperor Nero used it as an eyeglass 2,000 years ago, and much later, aquamarines were used as glasses in Germany to correct shortsightedness. In fact, the German name for eyeglasses today is “brille”, derived from the mineral beryl.

The second birthstone for March is the bloodstone. It’s a favored material for carving religious subjects, particularly the crucifixion. One particularly famous carving was done by the Italian Matteo del Nassaro around 1525. In “The Descent from the Cross”, the carving was carefully crafted so that spots of red on the bloodstone represented the wounds of Christ and His drops of blood. According to legend, bloodstone was believed to have formed during the crucifixion of Christ. A Roman soldier–guard thrust his spear into Christ’s side and drops of blood fell on some pieces of dark green jasper lying at the foot of the cross, and the bloodstone was created.

Bloodstone–also known as heliotrope–is a form of the abundant mineral quartz. This particular form of quartz, known as cryptocrystaline quartz, exists as a mass of tiny quartz crystals formed together in large lumps that show no external crystal form, yet each of the component crystals that make up the mass is a genuine crystal. This quartz variety is also called chalcedony. Green chalcedony, spotted with flecks of red is known as bloodstone. Bloodstone can be found embedded in rocks, or as pebbles in riverbeds. The best sources of this stone are India, Brazil and Australia.

Babylonians used this stone to make seals and amulets, and it was also a favorite with Roman gladiators. In the Middle ages, bloodstone was believed to hold healing powers, particularly for stopping nosebleeds. Powdered and mixed with honey and white of egg, it was believed to cure tumors and stop all types of hemorrhage. Ancient alchemists used it to treat blood disorders, including blood poisoning and stopping the flow of blood from a wound. Bloodstone was also believed to draw out the poison of snakes.

April – Diamond

April’s birthstone is the diamond. Diamonds are a wonder of nature. Their cold sparkling fire has held us spell–bound for centuries, inspiring rich passionate myths of romance, intrigue, power, greed, and magic. Ancient Hindus, finding diamonds washed out of the ground after thunderstorms, believed they were created by bolts of lightning. In our place and time, the diamond is a symbol of enduring love, and often grace engagement rings.

There are many kinds of diamonds: transparent, translucent or opaque; ranging from colorless to sooty black, with many colors in between. Mostly transparent diamonds, colorless or tinted, are used as jewelry. Others are used widely in industry. The color of a diamond depends on the kind of impurities embedded inside it. Yellow diamonds, for example, betray minute quantities of nitrogen, while boron imparts a bluish hue. There are other inclusions in diamonds that have great scientific value. Such samples are time capsules that yield valuable information about conditions deep in the Earth’s upper mantle where diamonds formed, and yield clues to the formation and age of the diamond.

Diamonds are the rich cousins of graphite, both crystalline forms of pure carbon. The enormous differences in their properties is a result of the way that carbon atoms are bonded together. In graphite, carbon atoms are arranged in sheets that easily slide past each other, making them ideal as lubricants and of course, pencil leads. Diamond crystals, on the other hand, are a “tight–fisted network of carbon atoms securely held in four directions, making it the hardest naturally–occuring substance in the world.

In order to achieve such a compact and strongly–held network of carbon atoms, it is believed that diamonds must have crystallized deep under the Earth’s surface. At these depths exist the proper conditions for the formation of diamonds; at 90 to 120 miles deep, pressures are more than 65,000 times that of the atmosphere at the Earth’s surface, with temperatures exceeding 2,700 degrees Fahrenheit. Such pressures and temperatures reproduced in laboratories have successfully yielded synthetic diamonds.

Diamonds are found in alluvial deposits–gravel swept by streams, rivers, glaciers and ocean currents. They are also found in sedimentary rock where gravel deposits and organic material have been compressed into rock. Diamonds can be found in some samples of kimberlite–a type of volcanic rock first identified in Kimberly, South Africa. Diamonds found in kimberlite are thought to be very old, perhaps as much as three billion years old. Tiny flecks of diamond have even been found inside meteorites–bits of rocky space debris that land on Earth.

Diamonds are crystals, crystals being the ultimate form of symmetry in nature. The shape of the crystal reflects the internal orderly arrangement of atoms within it. In diamonds, atoms of carbon are held tightly by covalent bonding, where two neighboring atoms share an electron, endowing the diamond crystal with great strength. But despite its hardness, diamonds can be cut. This is accomplished by cutting the gem along planes parallel to the faces of the crystal where the tight bonds between carbon atoms are a little weaker. Found in their natural form, diamonds can appear quite unimpressive. It is only when they are cut and polished by skilled craftsmen, such that the light entering it is reflected and refracted as best possible, only then is their hidden beauty revealed.

Some diamonds seem to have lived lives of their own. One legendary stone of the diamond hall of fame is the Koh–i–noor diamond. The Koh–i–noor’s early history is shrouded in time. It is believed to be 5,000 years old, and was featured in the great Sanskrit epic “The Mahabharata”. Originally owned by the Rajah of Malwa in India, the Koh–i–noor has since been a player in victories and defeats spanning India, Persia and Afghanistan. It was in the possession of the great Mogul dynasty from 1526 to 1739, its owners included Shah Jehan who built the Taj Mahal in memory of his queen Mumtaz. The Persian invader Nadir Shah briefly possessed it until his assassination in 1747. The jewel then fell into the hands of Afghan rulers who eventually surrendered it to the Rajah of Punjab, Ranjit Singh.

Two years after Ranjit Singh’s death in 1839, Punjab became part of India under British rule. The stone was presented to Queen Victoria who had it cut from its original 187 carats to 108 carats in an attempt to further enhance its beauty. After her death, the diamond became part of the British Regalia, and was worn by Queen Elizabeth, the Queen Mother in her 1937 coronation. Today, the Koh–i–noor diamond is worn as a brooch by the Queen Mother on ceremonial occasions.

May – Emerald

May’s birthstone is the emerald. Several famous historical artifacts were made of emeralds. Among them was the Crown of Andes, said to be worn by the last Inca king of Peru who was taken prisoner by Conquistador Pizzaro in 1532. The crown was said to be set with 453 emeralds, collectively weighing 10 ounces (1523 carats). In the 1940s, the crown was sold to, then broken up by, an American syndicate. Many of its stones are probably in the jewelry collections of wealthy Americans today.

Emeralds vary in color from light to deep green. It’s commonly thought that an emerald’s color derives from the presence of chromium and / or vanadium, replacing some of the aluminum in the mineral’s structure. The stone can, however, lose its color when heated strongly.

The emerald belongs to the beryl family of minerals that include aquamarine (the March birthstone), heliodor and morganite. Beryl, or beryllium aluminum silicate in chemical jargon, is a six–sided symmetrical crystal.Beryl contains beryllium, aluminum, silicon and oxygen.

The synthetic manufacturing of emeralds was achieved by German chemists shortly before World War II. But growing synthetic stones of fine quality began in the United States in 1946. There are also excellent imitation emeralds on the market made of colored cut glass.

Emeralds are most frequently found inside a form of shale–a fine grained sedimentary rock. Emerald–bearing shale has undergone recrystallization due to changes in the physical environment such as pressure and temperature. Colombia produces the largest and highest quality emeralds. They were also discovered, and subsequently mined, in the Ural Mountains of Russia around 1830. In the United States, emeralds can be found in North Carolina. Around the world, they also occur in Zambia, Brazil, Pakistan, Norway, Austria, India, Malagasy and Australia.

The emerald’s name is indirectly derived from the Greek word “smaragdos,” a term ambiguously applied to several kinds of green stones. The history of emeralds can be traced back to antiquity. They were worn by royalty in Babylon and Egypt. Tools dating back to 1300 B.C., during the reign of Rameses II, have been found in emerald mines in Egypt. Queen Cleopatra’s emeralds were believed to originate from mines in Southern Egypt, near the Red Sea.

When the conquistadors first arrived in South America from Spain, they saw native rulers wearing emeralds. Large quantities of emeralds were taken from Peruvians during the invasion but the source of the emeralds were never discovered. Then in 1537, the Spaniards found Chivor in Colombia, now the location of an important emerald mine. They also took over the Muzo mine following the defeat of the Muzo Indians. Mining operations at Muzo have continued almost uninterrupted since the Spanish invasion. It is now perhaps the most famous emerald mine in Colombia and is said to produce the world’s best emeralds.

There are many myths associated with the emerald. The stone was once believed to prevent epilepsy, stop bleeding, cure dysentery and fever, and protect the wearer from panic. Its magnificent green color was said to rest and relieve the eye. To the ancient Romans, emeralds were dedicated to the goddess Venus because it symbolized the reproductive forces of nature. Early Christians saw it as a symbol of the resurrection of Christ. In the Middle Ages, emeralds were believed to hold the power to foretell the future.

The Holy Grail Cup at the Cathedral in Genoa, Italy is said to be over 700 years old. Legend has it that it was taken from King Herod’s banquet table by the Disciples to be used by Jesus at the Last Supper. In the twelfth century, Crusaders returning from the Holy Land brought the Grail to Genoa.

June – Pearl, Moonstone & Alexandrite

June has no less than three traditional birthstones–pearls, moonstone, and Alexandrite. Pearls, according to Indian mythology, were dewdrops from heaven that fell into the sea. They were caught by shellfish under the first rays of the rising sun, during a period of full moon. In India, warriors encrusted their swords with pearls to symbolize the tears and sorrow that a sword brings.

Unlike most gemstones that are found within the Earth, pearls have an organic origin. They are created within certain species of oysters and clams. Some pearls are found naturally in mollusks that inhabit the sea or fresh water settings such as rivers. However, many pearls today are cultured–raised in oyster farms that sustain a thriving pearl industry. Pearls are made mostly of aragonite, a relatively soft carbonate mineral (CaCO3) that also makes up the shells of mollusks.

A pearl is created when a very small fragment of rock, sand grain or parasite enters the oyster or clam. It irritates the mollusk, who responds by coating the foreign material with layer upon layer of shell material. Pearls formed on the inside of the shell are usually irregular in shape and have little commercial value. However, those formed within the tissue of the mollusk are either spherical or pear–shaped, and are highly sought out for jewelry.

Pearls possess a uniquely delicate translucence and luster that place them among the most highly valued of gemstones. The color of the pearl depends very much on the species of mollusk that produced it, and its environment. White is perhaps the best–known and most common color. However, some pearls also come in delicate shades of black, cream, gray, blue, yellow, lavender, green and mauve. Black pearls can be found in the Gulf of Mexico and waters off some islands in the Pacific Ocean. The Persian Gulf and Sri Lanka are well–known for exquisite cream–colored pearls called Orientals. Other localities for natural seawater pearls include the waters off Celebes in Indonesia, the Gulf of California and the Pacific coast of Mexico. The Mississippi River, and forest streams of Bavaria in Central Europe contain pearl–producing freshwater mussels.

Japan is famous for its cultured pearls. Everyone familiar with jewelry has heard of Mikimoto pearls, named after the creator of the industry, Kokichi Mikimoto. Some cultured pearls are bred in large oyster beds in Japanese waters. An “irritant”, such as a tiny fragment of mother–of–pearl, is introduced into the fleshy part of two to three year–old oysters. The oysters are then grown in mesh bags submerged beneath the water and regularly fed for as long as seven to nine years before being harvested to remove their pearls. Cultured pearl industries are also carried out in Australia and equatorial islands of the Pacific.

The largest pearl in the world is believed to be about three inches long and two inches across, weighing one–third of a pound. Called the Pearl of Asia, it was a gift from Shah Jahan of India to his favorite wife, for whom he also built the Taj Mahal.

La Peregrina (the Wanderer) is considered by many experts to be the most beautiful pearl. It was said to be originally found by a slave in Panama four–hundred years ago, who gave it up in return for his freedom. In 1570, the conquistadors sent the pearl to King Philip II of Spain. This pear–shaped white pearl, one and a half inches in length, hangs from a platinum mount studded with diamonds. The pearl was passed to Mary I of England, then to Prince Louis Napoleon of France. He sold it to the British Marquis of Abercon, but then it disappeared for a century only to turn up once again at a New York auction house in 1969. The pearl was purchased by actor Richard Burton for his wife, Elizabeth Taylor.

Pearls were also widely used as medicine in Europe until the 17th century. Arabs and Persians believed it was a cure for various kinds of diseases, as well as insanity. Pearls have also been used as medicine as early as 2000 BC in China, where it was believed to represent wealth, power and longevity. Even to this day, lowest–grade pearls are ground for use as medicine in the Orient.

June’s second birthstone is the moonstone. The ancient Roman natural historian, Pliny, said that the moonstone changed in appearance with the phases of the moon, a belief that persisted until the sixteenth century. The ancient Romans also believed that the image of Diana, goddess of the moon, was enclosed within it. Moonstones were believed to have the power to bring victory, health and wisdom to those who wore it. In India, the moonstone is considered a sacred stone, often displayed on a yellow cloth, also considered a sacred color. The stone is believed to bring good fortune, brought on by a spirit that lives within the stone.

Moonstones are believed to be named for the bluish white spots within them, that when held up to light, project a silvery play of color very much like the moon. When the stone is moved back and forth, the brilliant silvery rays appear to move about, like moonbeams playing over water.

This gemstone belongs to the family of minerals called feldspars, an important group of silicate minerals commonly formed in rocks. About half the Earth’s crust is composed of feldspar. This mineral occurs in many igneous and metamorphic rocks, and also constitute a large percentage of soils and marine clays.

Rare geologic conditions produce gem varieties of feldspar such as moonstone, labradorite, amazonite and sunstone. They appear as large clean mineral grains, found in pegmatites (coarse–grained igneous rock) and ancient deep crustal rocks. Feldspars of gem quality are aluminosilicates, minerals containing aluminum, silicon and oxygen, that are mixed with sodium and potassium. The best moonstones are from Sri Lanka. They are also found in the Alps, Malagasy, Burma and India.

June’s third birthstone is the Alexandrite. The stone is named after Prince Alexander of Russia (which is why the “A” in Alexandrite is capitalized), who was to later become Czar Alexander II in 1855). Discovered in 1839 on the day of the prince’s birthday, Alexandrite was found in an emerald mine in the Ural Mountains of Russia. Because it is a relatively recent discovery, there has been little time for myth and superstition to build around this unusual stone. In Russia, the stone was also popular because it reflected the Russian national colors, green and red, and was believed to bring good luck.

The Alexandrite possesses an enchanting chameleon–like personality. In daylight, it appears as a beautiful green, sometimes with a bluish cast or with a brownish tint. However, under artificial lighting, the stone turns reddish–violet or violet.

Alexandrite belongs to the chrysoberyl family, a mineral called beryllium aluminum oxide in chemistry jargon, that contains the elements beryllium, aluminum and oxygen (BeAl2O4). This is a hard mineral, only surpassed in hardness by diamonds and corundum (sapphires and rubies). The unusual colors in Alexandrite are attributed to the presence of chromium in the mineral. Chrysoberyl is found to crystallize in pegmatites (very coarse–grained igneous rock, crystallized from magma) rich in beryllium. They are also found in alluvial deposits–weathered pegmatites containing the gemstones that are carried by rivers and streams.

Alexandrite is an uncommon stone, and therefore very expensive. Sri Lanka is the main source of Alexandrite today, and the stones have also been found in Brazil, Malagasy, Zimbabwe, Tanzania and Burma. Synthetic Alexandrite, resembling a reddish–hued amethyst with a tinge of green, has been manufactured but the color change seen from natural to artificial lighting cannot be reproduced. Such stones have met with only marginal market success in the United States.

July – Ruby

The ruby, birthstone for July, is among the most highly prized of gemstones. Large rubies are harder to find than large diamonds, emeralds and sapphires. As a result, rubies’ value increases with size more than any other gemstone.

In the Orient, rubies were once believed to contain the spark of life–”a deep drop of the heart’s blood of Mother Earth”, according to ancient Eastern legends. Ancient Orientals believed that the ruby was self–luminous. They called it “glowing stone” or “lamp stone.” It’s said that an Emperor of China once used a large ruby to light his chamber, where it glowed as bright as day. Brahmans–Hindu priests of the highest caste–believed that the homes of the gods were lit by enormous emeralds and rubies. Later, Greek legends told the story of a female stork, who repaid the kindness of Heraclea by bringing her a brilliant ruby–a ruby so bright that it illuminated Heraclea’s room at night.

Along with its close relative, the sapphire, the ruby is a form of the mineral corundum, which is normally drab and grey in color. Red gemstone corundum is called ruby. All other gemstone corundum colors–orange, yellow, brown, green, blue, purple, violet, black, and colorless–are called sapphires.

Ancient Hindus, Burmese and Ceylonese regarded sapphires as unripe rubies, believing that if they buried the sapphire in the ground, it would mature to a rich red ruby.

The word ruby is derived from the Latin ‘ruber’, meaning red. This name was once used to describe all red stones, including red spinel, red tourmaline and red garnet. Many famous rubies in history turned out not to be rubies after all. For example, the famed Timur ruby–given to Queen Victoria in 1851–was later found to be ruby spinel.

The Mogok valley of Upper Burma is famous as the source for the finest and rarest rubies of all, know as “pigeon’s blood” for the stones’ intense red color. Another major source of rubies is Thailand, well–known for dark, brownish–red rubies. Both Thailand and Burma regard the ruby as their national stone.

In the Middle Ages, rubies were thought to bring good health, as well as guard against wicked thoughts, amorous desires and disputes. Rubies, along with other types of red stones, were said to cure bleeding. And it was believed that the ruby held the power to warn its owner of coming misfortunes, illness or death, by turning darker in color. It is said that Catherine of Aragon, first wife of King Henry VIII, predicted her downfall in seeing the darkening of her ruby.

Because of their rarity, there are very few famous large rubies. In his 13th century books of his travels, Marco Polo relates the tale of a magnificent gemstone–believed to be a ruby nine inches long and as thick as a man’s arm–belonging to the King of Ceylon. Kublai Khan, the Emperor of China offered an entire city in exchange for the enormous stone, to which the King of Ceylon replied that he would never part with his prize for all the treasures of the world.

August – Peridot & Sardonyx

August has two birthstones, Peridot and Sardonyx. The peridot was regarded since ancient times as the symbol of the sun. The Greeks believed that it brought royal dignity upon its wearer. During the Middle Ages, peridot was pierced, then strung on the hair of an ass and attached to the left arm to ward off evil spirits. The Crusaders thought that peridots were emeralds, and brought them back to Europe where they were featured as ornaments in churches.

Peridot is a gem–quality transparent variety of olivine, a mineral composed of magnesium–iron silicates. The color of olivine ranges from olive to lime green, sometimes with a brownish tinge. The green color is due to the presence of iron, while the brownish tinge indicates a higher iron content.

Some of the finest peridot stones are called “evening emeralds” because they appear greener under artificial light.

An island in the Red Sea–named Zabargad, which means olivine in Arabic–has been mined for peridot since ancient times. It is a small desolate island–nothing grows, there is no fresh water, and it is scorchingly hot all year round except the middle of winter. In some locations on the island, fissures are lined with gem crystals ranging from millimeters to several centimeters. Beaches near the deposits have a greenish hue due to tiny green peridot crystals.

Peridot crystals are also found in the Mogok district of Burma, Norway, Brazil, China, Kenya, Sri Lanka, Australia, and Mexico. In the United States, small stones can be found in the San Carlos Indian Reservation in Arizona. Peridot has also been found in some meteorites.

Peridot is among the oldest known gemstones. The “topaz” on the breastplate of Aaron, High Priest of the Hebrews in the Old Testament, was believed to actually be peridot. Ancient Egyptians, around 1580 B.C. to 1350 B.C., created beads from peridot. For Greeks and Romans, peridot was in popular use as intaglios, rings, inlays, and pendants.

Peridots were a prized gem late in the Ottoman empire (1300–1918). Turkish Sultans collected what is believed to be the world’s largest collection. The gold throne in Istanbul’s Topkapi museum is decorated with 955 peridot cabochons (gems or beads cut in convex form and highly polished) up to 1 inch across, and there are also peridots used as turban ornaments and on jeweled boxes. The largest stone is believed to be a 310 carat gem that belongs to the Smithsonian. A 192 carat stone of fine clear olive–green is part of the Russian crown jewels, in the Kremlin.

A second August birthstone is Sardonyx. Roman soldiers wore sardonyx talismans (objects bearing a sign of astrological influence to guard from evil and bring good fortune) engraved with heroes such as Hercules or Mars, god of war. They believed that the stone would make the wearer as brave and daring as the figured carved on it. During the Renaissance, sardonyx was believed to bring eloquence upon the wearer and was regarded with great value by public speakers and orators.

Sardonyx is a variety of the silica mineral called chalcedony. This sort of mineral contains layers of tiny quartz fibers, which are stacked on top of each other to give a banded appearance. The layers in these stones range from translucent to opaque. The stones vary in color, too. They may be white or gray, ranging to many colorful varieties.

Sardonyx stones usually contain flat–banded, white and brownish–red bands. The word Sardonyx is derived from the Greek, Sard meaning “reddish brown,” and onyx meaning “veined gem.” The best stones are found in India. They are also found in Germany, Czechoslovakia, Brazil, and Uruguay. In the United States, sardonyx can be found in the Lake Superior region and in Oregon.

Cameos and intaglios are often carved from Sardonyx. Cameos are figures carved on a stone, where the white layer appears as relief, and the colored layer is the background. Intaglios are the reverse of cameos. They are incised figures on the stone, where the stone is carved through the dark layer to reveal the light layer.

Sardonyx is a relatively common and inexpensive gemstone. It was a favorite gemstone in ancient times, popular not only because it was attractive, but also because it was widely available. Unlike most rare gemstones that could only be bought with the wealth of royalty and nobility, sardonyx could be obtained by many less–wealthy people.

Perhaps the most famous sardonyx stone was set in a gold ring, carved with the portrait of Queen Elizabeth I of England. It was given to the Earl of Essex by the Queen as a token of friendship, and she assured him that she would always come to his aid if he ever requested it. The Earl, imprisoned for treason, was condemned to be beheaded. He tried to send the ring to his Queen but it fell into the hands of Lady Nottingham, whose husband was an enemy of the Earl of Essex. Thinking that the Earl was too proud to ask for her mercy, the Queen allowed his execution. It wasn’t until the deathbed confession of Lady Nottingham that the Queen learned the truth, which left her heart–broken.

September – Sapphire

The sapphire, birthstone for September, is a relative of July’s birthstone, ruby. Like ruby, it is a form of the mineral corundum, a normally drab grey mineral. Red corundum is called the ruby, while all other gem quality forms of corundum are called sapphires.

Typically, sapphires appear as blue stones, ranging from very pale blue to deep indigo, due to the presence of small amounts of titanium and iron within the crystal structure. The most valued shade of blue is the medium–deep cornflower blue. Sapphires also occur in other natural colors and tints–colorless, gray, yellow, pale pink, orange, green, violet and brown–called fancy sapphires. These different colors are caused by different kinds of impurities within the crystal. For example, yellow sapphires get their color from ferric iron, and colorless gems have no contaminants.

The word “sapphire” has its roots in several ancient languages: the Arabic “safir,” the Latin “sapphirus” (meaning “blue”), and the Greek word “sappheiros” for the island of Sappherine in the Arabian Sea where sapphires were found in ancient Grecian times. Ancient Persians called sapphire the “Celestial Stone.” It was the gem of Apollo, Greek God of prophesy and was worn by his worshipers visiting his shrine in Delphi to seek his help. It was used by ancient Etruscans as far back as the 7th century B.C.

The biggest source of sapphires world–wide is Australia, especially New South Wales and Queensland. Found in alluvial deposits of weathered basalt, Australian sapphires typically are blue stones with a dark and inky appearance. Kashmir, in India, used to be a well–known source of the cornflower–blue stones. In the United States, a major source is the Yogo Gulch Mine in Montana that mostly yields small stones for industrial use.

The sapphire was said to represent the purity of the soul. Before and during the Middle Ages, it was worn by priests as protection from impure thoughts and temptations of the flesh. Medieval kings of Europe valued these stones for rings and brooches, believing that it protected them from harm and envy. Warriors presented their young wives with sapphire necklaces so they would remain faithful. It was believed that the stone’s color would darken if worn by an adulterer or adulteress, or by an unworthy person.

Sapphires were once believed to be protection against snakes. It was said that if poisonous reptiles and spiders were placed in a jar containing the stone, the creatures would immediately die. The French of the 13th century believed that sapphire transformed stupidity to wisdom, and irritability to good temper.

One of the most famous sapphires rests on the Imperial State Crown, worn by Queen Victoria in 1838. It resides in the British Crown Jewels in the Tower of London. This gem is called the St. Edward’s Sapphire because it once belonged to Edward the Confessor, who wore the stone on a ring during his coronation in 1042.

October – Opal & Tourmaline

October has two birthstones–opal and tourmaline.

The name opal is derived from the Sanskrit word “upala,” as well as the Latin “opalus,” meaning “precious stone.” Opal is a gemstone of much variety; the ancient Roman natural historian Pliny once described it in the following way:

“… it is made up of the glories of the most precious stones. To describe it is a matter of inexpressive difficulty: There is in it the gentler fire of the ruby, the brilliant purple of the amethyst, the sea–green of the emerald, all shining together in an incredible union.”

The opal is a fragile hydrated silica material, made of submicroscopic silica spheres held together by more silica and water. It is a soft stone, easily altered in appearance by changes in heat and pressure. This mineral contains varying amounts of water within it that determine the appearance of the gemstone. When water evaporates out of an opal, the stone appears slightly smaller and the stress of the evaporation creates cracks on it.

Opals are formed in near–surface volcanic rocks, within cavities and cracks. In sedimentary volcanic ash rock, percolating water in the ground dissolves silica that eventually precipitates to form the opal, sometimes becoming the replacement material for fossils–shells, bones, wood–whose original material had dissolved away.

Opals are famous for their “play of colors”–many stones flash the colors of the rainbow when moved, due to the interference of light on small cracks and other internal structural differences. Opals also have characteristic colors due to impurities within the stone. The milky or pearly appearance of some opals are due to inclusions of tiny gas bubbles. Yellows and reds betray the presence of iron oxides. The spectacular black opals that sometimes flash green, blue and red get their color from magnesium oxides and organic carbon within the stone. Perhaps the most valuable opal pattern is the “harlequin,” large angular patches of red, yellow and green resembling the checks on a clown’s costume.

The principal source of opals is Australia, noted for its magnificent black opals. Fire opals were first mined in Mexico, and continue to be produced today. In the United States, brilliant fire opals are also found in Nevada. Other commercial sources of opal are Brazil, Honduras, Nicaragua, Guatemala, Japan and Ireland.

There is an Indian legend about the origin of the opal. Quoted from “Gemstones” by Willard Heaps:

“…the gods Brahma, Vishnu and Shiva once vied in jealous love for a beautiful woman. This angered the Eternal, who changed the fair mortal into a creature made of mist. Thereupon each of the three gods endowed her with his own color so as to be able to recognise her. Brahma gave her the glorious blue of the heavens, Vishnu enriched her with the splendor of gold, and Shiva lent her his flaming red. But all this was in vain, since the lovely phantom was whisked away by the winds. Finally, the Eternal took pity on her and transformed her into a stone, the opal, that sparkles in all the colors of the rainbow.”

To ancient Romans, the opal was a symbol of love and hope. Orientals called it the “anchor of hope.” Arabs say it fell from the heavens in flashes of lightning. It was believed to make its wearer invisible, hence the opal was the talisman of thieves and spies.

During the Medieval period, a change in color intensity of an opal was believed to indicated if its wearer was ill or in good health. The opal was supposed to maintain a strong heart, prevent fainting, protect against infection, and cleanse foul–smelling air. The stone, as in ancient times, was still regarded as a symbol of hope.

But the opal’s reputation changed in the mid–14th century. The Black Death swept across Europe, killing one quarter of its population. The gem was believed to be the cause of death. When worn by someone struck with the deadly plague, it would appear brilliant only until the person died. Then it would change in appearance, losing its luster. In reality, it was the sensitivity of this stone to changes in temperature that altered its appearance, as the heat from a burning fever gave way to the chill of death.

In Elizabethan England, the opal was treasured for its beauty. Shakespeare wrote of it in the Twelfth Night as the “queen of gems.” Queen Victoria presented her children with opal jewelry, thus making the the stone popular. But the stone continued to have a mixed reputation, chiefly due to a novel written by Sir Walter Scott in 1887 that depicted it as a stone of evil.

In Australia, there is a legend of a huge opal that governs the stars and guides human love, as well as controls the gold in mines. But Australian aborigines see it in a different light–to them, the opal is the devil that lurks in the ground, a half–serpent and half–human with flashes of wicked magic that lures men to destruction.

The alternate birthstone for October is the tourmaline, a gemstone that exhibits the broadest spectrum of gemstone colors. Gem–quality forms of this mineral have in the past been misidentified as rubies, emeralds and sapphires. In fact, a famous tourmaline–the size of a pigeon’s egg–belonging to the Russian Empress Catherine the Great was long thought to be a ruby. The name of this gemstone is believed to derive from the Singhalese (Sri Lankan) word “toramalli,” a term applied to yellow, green or brown stones, that means “something little out of the earth.”

Tourmaline is a complex aluminous borosilicate mineral built of crystals with complicated aggregations of sodium, aluminum, boron, oxygen, hydrogen and silicon atoms. Other metals are also present within the crystal structure, and are responsible for the characteristic colors of the gemstones. Pink, for example, is due to the presence of manganese, while ferrous iron, chromium or vanadium betray their presence as green gemstones.

Most tourmalines are found in a myriad of colors: yellow, green, red, blue, pink, brown, black. Some even have bi–colored properties. A valued bi–colored variety of tourmaline, found in Brazil, is called the “watermelon.” The outer edges of the gem are green, transitioning to a transparent white zone that gives way to a pink or light red interior.

Tourmaline has an unusual property. When it is warmed or rubbed, it attracts small bits of paper, lint and ash. This occurs because the gem becomes charged with static electricity. In fact, Benjamin Franklin used this gem in his studies of electricity. Maintaining a tourmaline exhibit at museums requires frequent cleaning of the gemstone because heat from lights of the display case create a charge in the stone that attracts dust.

Compared with other gemstones, tourmalines are a relatively recent discovery. Hence, it lacks the rich lore that accompanies many other precious gems. However, among some people, the stone is known as the “peace stone,” believed to dispel fear and make its wearer calm.

November – Topaz

The name topaz, birthstone for the month of November, comes from a Sanskrit word meaning “fire.” And in ancient lore, it could be used to control heat. It was said to have the power to cool boiling water, as well as excessive anger. As medication, topaz was used to cure fever.

Topaz occurs in a range of magnificent colors–blue, pale green, varying shades of yellow, pink, red, brown and even black. Pure topaz itself is a colorless stone. Red and some pink topaz get their colors from chromium that is substituted for aluminum in the crystals. But most other colors occur due to minor element substitutions and defects in the crystal. Some colors are unstable and can fade away; for example, brown topaz mined in Siberia can be bleached by sunlight. In other stones, color changes can be induced by heating. High energy irradiation and moderate heat treatment of colorless topaz can transform it to blue gemstones.

Chemically, topaz is known as aluminum silicate fluoride hydroxide. Because of strong chemical bonds within this mineral, topaz is the hardest of silicate minerals. Topaz gemstones occur in a large variety of sizes, from tiny crystals to large rocks. The biggest uncut stone, a specimen found in Brazil weighing almost 600 pounds, is on display at the American Museum of Natural History in New York. A famous cut topaz in history is found among the crown jewels of Portugal, a magnificent yellow stone weighing 12 ounces.

This gem, with its lively fire, clarity, beautiful colors and hardness is ideal for jewelry such as clips, necklaces, brooches and bracelets. Pure topaz, when brilliantly cut, can be often mistaken for a diamond. Because of its rarity, topaz is an expensive gem. The most valued and rarest color is red. Imperial topaz–sherry colored varieties of brownish–yellow, orangy yellow and reddish brown–are the most popular topaz stones and command high prices, as do pink colored stones. Light blue and pale yellow topaz are of less value, but are nevertheless stunning in beauty.

Brazil is the largest producer of topaz, the most notable source being the Minas Geranis region. Gems are also found in Russia, the Ukraine, Pakistan, Scotland, Japan and Sri Lanka. In the United States, the gemstones have been found in Colorado and California.

During the Middle Ages, the topaz was used mostly by royalty and clergy. A 13th century belief held that a topaz engraved with a falcon helped its wearer cultivate the goodwill of kings, princes and magnates.

Topaz was once thought to strengthen the mind, increase wisdom, and prevent mental disorders. It was thought to guard against sudden death. Powdered topaz added to wine was used to prevent asthma and insomnia. A cure for weak vision called for immersing the stone in wine for three days and nights, then rubbing the liquid on the eyes.

December – Turquoise & Zircon

December has two birthstones, turquoise and zircon. Turquoise is considered by some to be a symbol of good fortune and success, believed to bring prosperity to its wearer. Its name is believed to originate from the French phrase “pierre turquoise” meaning “Turkish stone” because turquoise was brought to Europe by Venetian merchants who first acquired it in Turkish bazaars. It is also considered by some as a love charm. When received as a gift, the turquoise symbolizes a pledge of affection. Shakespeare used this lore in “The Merchant of Venice’. In it, Leah gave a turquoise ring to Shylock when he was a bachelor, hoping it would win his affections so he would ask her to marry him. In Russia, the turquoise is popularly used in wedding rings.

In the language of chemists and geologists, turquoise is known as “copper aluminum phosphate.” Turquoise is often found in weathered igneous rock that contains copper minerals, where it crystallizes in veins and nodules. The gemstone usually develops in rock near water tables, located in semiarid and arid environments. The chemicals in turquoise come from adjacent rock, leached out by rain and groundwater.

Turquoise is a relatively soft gemstone, and can be easily scratched and broken. This porous opaque stone is easily discolored by oil and pigments, and changes color when it loses some of its water content. A sky blue shade in turquoise is due to the presence of copper, while iron gives it a greener tone. Ochre and brown–black veins in the stone occur during the formation of turquoise, caused by inclusions from nearby rock fragments or from oxide staining. The most valued variety of turquoise is an intense sky blue color, like the color of a robin’s egg. Hard, relatively non–porous compact stones have the best appearance because the stone can be finely polished. Pale and chalky varieties however are sometimes impregnated with oil, paraffin, liquid plastic and glycerin to give it a good polish.

This stone can be found in Armenia, Kazakhstan, China, Australia, Tibet, China, Mexico, Brazil, and Egypt. In Iran, where some of the best stones are found, turquoise is the national gem. The American southwest–Nevada, Arizona, Colorado, New Mexico and California–are primary producers of turquoise. Much of the specimens have a light color, and are porous and chalky–only about 10% is of gem quality.

Turquoise is one of the earliest known stones to be used in jewelry. Pharaohs of Early Egypt wore them. A tomb excavated in 1900 contained the mummified remains of Queen Zer, who ruled in 5500 B.C.; found on her arm were four magnificent turquoise bracelets. Beads dating back to 5000 B.C. have been found in Mesopotamia (now Iraq). In Iran, turquoise was the national gemstone, adorning thrones, daggers, sword hilts, horse trappings, bowls, cups, and ornamental objects. Senior officials wore turquoise seals decorated with pearls and rubies. In the 7th century A.D., turquoise pieces inscribed with passages from the Koran and Persian proverbs were valued amulets. It was used as jewelry in ancient Siberia, around the Fifth and Sixth century B.C.. During the Middle Ages, they were popularly used as decoration of vessels and covers for manuscripts. And it was again popular as jewelry during the Renaissance. It has also been found in ancient burial sites in Argentina, Bolivia, Chile, Peru, Mexico and Central America. The Incas crafted beads and figurines out of it, and the Aztecs made pendants and ritual masks.

Turquoise has a rich history in the American southwest. Native Americans have been using this gemstone to create magnificent jewelry and ornamental pieces for the past several thousand years. It was called “Chal–cui–hui–tal”, meaning “the highest and most valued thing in the world”. The Zuni, Hopi, Pueblo and Navajo Indians made magnificent necklaces, ear pendants and rings. The blue in turquoise symbolized the Heavens, and green symbolized the Earth. The stones were used by medicine men to work charms. The Navajo believed that turquoise pieces, thrown into a river while offering a prayer to the rain god, would bring much needed rain. Apache lore held that a turquoise attached to a bow or gun would ensure accurate aim.

There are many superstitions associated with the turquoise. In the Third century, it was believed to protect its owner from falling off a horse. A change in color revealed the infidelity of a wife. Twelfth century Arabian writings said “The turquoise shines when the air is pure and becomes pale when it is dim.” They also believed that its color changed with the weather. Persians said that the reflection of the new moon on a turquoise stone brought good luck, and guarded against evil. It was said to have a healing effect on the eye–merely looking at it strengthened the eye, while placing it on an inflammed eye brought a cure. A 15th century philosopher attributed its change of color to its ability to attract poisons. It was a barometer of its user’s health, turning pale in illness and losing color in death, yet regaining its original beauty in the hands of a new and healthy owner.

The alternate birthstone for December is the zircon. Its name is probably derived from the Arabic words “zar” and “gun”, meaning “gold” and “color”. The gemstone is found in a wide range of colors, and possess great brilliance, fire and clarity.

Zircon, in its unchanged natural form appears colorless to pale yellow, or green. These colors are caused by minute quantities of thorium and uranium that replaces zircon in the crystal structure. But over the vast spans of geologic time, other forces work within the zirconium silicate crystals. The uranium and thorium inclusions emit radiation that alters the original crystal structure. A glass–like material is formed, with colors of red to brown, orange and yellow.

The mineral zircon, known as zirconium silicate, is commonly found as a minor constituent in igneous rock such as granites and some kinds of metamorphic rock. Gem quality zircon stones are usually rare. These gemstones are formed mainly in pegmatites (coarse–grained igneous rock) and in fissures. But due to weathering of the gem–bearing rocks, most zircons are found in alluvial and beach deposits.

A new blue color for zircon, called “starlight blue,” was created by heating golden brown or yellow zircon in the 1920s. From Gems and Crystals by Anna S. Sofianides and George E. Harlow:

In the 1920s, a new blue gemstone suddenly appeared in the market. Endowed with spectacular brilliance, it was an immediate hit. The gems were zircons, normally brown to green – but not blue. George F. Kunz, the legendary Tiffany gemologist, immediately suspected trickery; not only were there extraordinary stones available in abundance but available all over the world! Upon Kunz’s behest, a colleague made inquiries during a trip to Siam (Thailand) and learned that a large deposit of unattractive brown zircon had stimulated color– improvement experimentation by local entrepreneurs. Heating in an oxygen–free environment had turned the drab material into “new” blue stones, which were sent to outlets worldwide. When the deception was revealed, the market simply accepted the information, and the demand for the new gems continued unabated.

The most prized zircon is the red gemstone, which is rare. The pure intense blue and sky blue varieties are also highly valued, while the colorless, orange, brown and yellow stones are less expensive. Many zircons on the market are heat treated, and sold as blue, golden brown or colorless stones. Colorless zircons are the best imitators of diamonds, in appearance only, with a brilliant fire that is almost as dazzling as the real thing. However, the resemblance is superficial. Zircon is a brittle stone, easily broken with a well–placed knock, due to internal stresses in the crystal caused by radiation damage and heat treatment. But despite its frail disposition, the stone is still highly valued because of its stunning beauty.

Major sources of zircon are the Chanthaburi area of Thailand, the Palin area of Cambodia and the southern part of Vietnam near the Cambodian border, where gemstones are found in alluvial deposits. Bangkok is well–known as a major center for processing zircons, where everything from heat treatment, cutting and marketing is carried out. Another important source is Sri Lanka, well known for a colorless variety of zircon called the ‘Matura diamond’. The gemstones are also found in Burma, France, Norway, Australia and Canada.

The hyacinth and jacinth, reddish–brown and orange–red varieties of zircon, were a favorite stone of ancient Arabs and was even mentioned in the famed book, ‘Arabian Nights’.

Green zircon was among the stones of the ‘Kalpa Tree’ of the Hindu religion, where it represented the tree’s foliage. This tree was a symbolic offering to the gods. Hindu poets of the 19th century described it as a glowing ensemble of precious stones that also included sapphires, diamonds and topaz.

Zircon was regarded as the amulet for travelers in the Eleventh century, protecting them from disease, injury, and insomnia, as well as assuring a cordial welcome wherever their travels would take them. The gem was also believed to hold magic powers to fight evil spirits. During the Fourteenth century, zircon was popular as a safeguard against the Black Death, the great plague that wiped out one quarter of the population of Europe. The stone was believed to possess healing powers. It was prescribed to insomniacs to induce sleep, used as an antidote against poison, and as an aid to digestion.

Resources

Birthstones, by Willard A. Heaps. Hawthorn Books. 1969.

A Book of Precious Stones, by Julius Wodiska. G.P. Putnam’s Sons, 1910.

The Concise Oxford Dictionary of Earth Science, edited by Ailsa Allaby and Michael Allaby. Published by Oxford Unievrsity Press, 1991.

Diamonds: Productions – Markerting – Buying – Grading – Appraising, by the Gemological Institute of America, 1980.

Gems and Crystals, by Anna S. Sofianides and George E. Harlow. Simon&Schuster, 1990.

Gemstones, by G.F. Herbert Smith, Pitman Publ. Co. 1958, revised 1972.

“New Date for Diamonds”, by Nick Rogers and Chris Hawkesworth, Nature, vol 310, 19 July 1984.

Planet Earth: Gemstones, by Paul O’Neil and the editors of Time–Life books. Time–Life books, 1983.

Rocks and Minerals, Herbert Zim and Paul Shaffer, Golden Press, NY, 1957.

The Science of Gems, by P.J. Fisher. Charles Scribner’s sons, NY, 1966.