November 11, 2019

If your birthday is in November, your birthstone—the gem associated with the month of your birth—is the topaz. Topaz is a compound of aluminum, fluorine, silicon, oxygen, and hydrogen. The mineral is commonly white or light colored, but trace impurities can give topaz crystals a wide variety of colors. Topaz is often cut into gems, and its myriad colors give it a lovely versatility in jewelry.

Topaz is the birthstone for the month of November. Credit: © Albert Russ, Shutterstock

The ancient Greeks believed topaz increased physical strength. In the Middle Ages, topaz was worn to ward off danger, break magic spells, or maintain good health. Topaz was also thought to improve eyesight and at times make a person invisible. People thought that beneath a pillow, topaz prevented nightmares, and in a home the gem protected from fires. Gold-colored topaz was thought to attract wealth as well as the favors of royalty or high government. In India, topaz was believed to encourage long life, beauty, and intelligence. “Imperial” topaz was a favorite gem of the Russian  czars.

Small amounts of topaz occur in both igneous rocks (rocks formed when molten rock cools and solidifies) and metamorphic rocks (rocks formed by heat and pressure). Jewelers cut transparent topaz crystals into gems. The most desirable topaz gems range in color from completely colorless to gold, orange, blue, and pink. Exposing some topaz crystals to heat or radiation can dramatically enhance or even change their color.

Jewelers sell blue topaz as a substitute for the gem aquamarine (a birthstone of March). Citrine, a yellow or brownish variety of quartz, is sometimes sold as a substitute for topaz. Topaz is found in many parts of the world. Brazil produces most of the world’s gem-quality topaz. Many museum collections have large, beautiful topaz crystals that weigh hundreds of pounds or kilograms. The gem gallery at the National Museum of Natural History at the Smithsonian Institution in Washington, D.C., is home to the 48.86-carat Whitney Flame Topaz. It is one of the finest imperial topaz gemstones in the world, notable for its large size and fiery red color.

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Birthstones, according to tradition, bring good luck when worn by a person born in the associated month. Credit: WORLD BOOK illustrations by Paul D. Turnbaugh

According to tradition, a birthstone brings good luck to a person born in its month. Each birthstone also corresponds to a sign of the zodiac. The belief in birthstones may have come from a Bible story about Aaron, the first high priest of the Israelites. The story describes Aaron’s breastplate, which was decorated with 12 precious stones. Early writers linked these stones with the 12 months of the year and the 12 signs of the zodiac. The custom of wearing a stone that represented a person’s zodiac sign probably originated in Germany or Poland in the 1700′s.

September 11, 2019

If your birthday is in September, your birthstone—the gem associated with the month of your birth—is the sapphire. The sapphire, a variety of the mineral corundum, is a hard and clear gem. The best known sapphires are blue. Their color results from small amounts of iron and titanium in the stone. Sapphires are also found in many other colors, including yellow, green, white, black, violet, and orange. The red variety of corundum is known as a ruby, the birthstone of July. Sapphires have long been used in jewelry and decorative objects.

Sapphires are shown cut and polished, left, and uncut, right. The sapphire is the birthstone of the month of September. Credit: © Biophoto Associates/Photo Researchers

Traditionally, sapphires symbolize faithfulness, nobility, purity, and sincerity. Sapphires were once thought to allow clarity of mind and to ward off evil spirits. As the stone of the planet Saturn, sapphires offered a magical portal to heavenly realms. In ancient Greece and Rome, sapphires protected people from envy and harm. The gems have long been popular with royalty, and Roman Catholic bishops and other clergy have worn sapphire rings for centuries. The sapphire’s rich blue color is used to describe blue objects of particular beauty, such as Sapphire Lake in northern California. The sapphire is the traditional gem gift for a 45th wedding anniversary. In 2017, Queen Elizabeth II became the first British monarch to mark a 65th year on the throne with a sapphire jubilee.

The most valuable sapphires once came from Indian Kashmir. They are a magnificent cornflower blue, the color to which all sapphires are compared. Today, Thailand is the most important source of blue sapphires. Blue and fancy sapphires are also found in the Sapphire Mountains (naturally) of Montana and in Australia, Myanmar, and Sri Lanka.

Lovely star sapphires contain needles of the mineral rutile that reflect light in six starlike rays. The most highly prized star sapphires are blue. Black or white star sapphires are less valuable. One of the largest blue star sapphires, the Star of India, weighs 563 carats, or about 4 ounces (110 grams). It is on exhibit in the American Museum of Natural History in New York City.

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Birthstones, according to tradition, bring good luck when worn by a person born in the associated month. Credit: WORLD BOOK illustrations by Paul D. Turnbaugh

According to tradition, a birthstone brings good luck to a person born in its month. Each birthstone also corresponds to a sign of the zodiac. The belief in birthstones may have come from a Bible story about Aaron, the first high priest of the Israelites. The story describes Aaron’s breastplate, which was decorated with 12 precious stones. Early writers linked these stones with the 12 months of the year and the 12 signs of the zodiac. The custom of wearing a stone that represented a person’s zodiac sign probably originated in Germany or Poland in the 1700′s.

August 19, 2019

If your birthday is in August, you have two birthstones—the gems associated with the month of your birth: peridot and sardonyx. Peridots are a variety of a common rock-forming mineral called olivine. A high iron content gives peridots their distinctive green color. The sardonyx is a multi-colored variety of chalcedony, a fine-grained form of the mineral quartz. Most sardonyx has straight or slightly curved bands of reddish-brown and white. Both peridot and sardonyx have long been used in jewelry and decorative objects.

Peridot is one of two August birthstones. The other is sardonyx. Credit: © Albert Russ, Shutterstock

Peridots have been known since Biblical times, and legend says the stones improve health, guard against insanity, and slow the human aging process. Peridots are also said to increase assertiveness, patience, and clarity of thought and to encourage prosperity and happiness. Jewelers cut and polish the highest-quality peridot stones so that each gem has many flat surfaces called facets. Faceted peridots are used in all types of fine jewelry. Jewelers cut lesser-quality peridots into a rounded style called cabochon or polish them with abrasives in a process called tumbling. These lesser-quality peridots are used in costume jewelry and decorative objects. The earliest source of peridots was Jazirat Zabarjad (St. John’s Island), off the Egyptian coast in the Red Sea. In the United States, Arizona and New Mexico are important commercial sources of peridots.

Sardonyx is a multi-colored variety of chalcedony. Credit: © Vlad3563/Dreamstime

In ancient Egypt, sardonyx was considered a protective stone, and it was used to ward off evil. Modern folklore credits sardonyx with encouraging confidence, creativity, happiness, integrity, optimism, and even virtuous behavior. It is said to help students preparing for exams, authors dealing with writers block, or anyone faced with a job requiring mental discipline. Jewelers usually cut sardonyx flat or with a domed shape to bring out the bands of color. Cameos (engraved gems) are sometimes cut from sardonyx to take advantage of its color. The chief sources of sardonyx are Brazil, India, and Uruguay.

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Birthstones, according to tradition, bring good luck when worn by a person born in the associated month. Credit: WORLD BOOK illustrations by Paul D. Turnbaugh

According to tradition, a birthstone brings good luck to a person born in its month. Each birthstone also corresponds to a sign of the zodiac. The belief in birthstones may have come from a Bible story about Aaron, the first high priest of the Israelites. The story describes Aaron’s breastplate, which was decorated with 12 precious stones. Early writers linked these stones with the 12 months of the year and the 12 signs of the zodiac. The custom of wearing a stone that represented a person’s zodiac sign probably originated in Germany or Poland in the 1700′s.

July 5, 2019

If your birthday is in July, your birthstone—the gem associated with the month of your birth—is the beautiful and valuable ruby. A red gem variety of the mineral corundum, rubies are called sapphires if they are any color other than red. Since ancient times, rubies have been treasured for their beauty as well as their symbolic value in folklore, religion, and superstition.

The ruby, the birthstone for July, is often used to make jewelry such as rings. This ring is set with a ruby and diamonds. Credit: © JupiterMedia/Alamy Images

Early cultures valued rubies for their resemblance in color to human blood, and the gems were thought to hold the power of life. Rubies were later associated with beauty, love, passion, wealth, and wisdom. Ancient Sanskrit texts refer to the ruby as “the king of precious stones,” and Hindu legend says that those who offered rubies to the god Krishna were granted rebirth as emperors. Rubies were thought to protect those who wore them, even bestowing invincibility in battle. It was not enough to simply wear rubies, however—they were often inserted in the skin. Rubies were also sometimes included in the foundations of buildings to ensure good fortune. Rubies have long adorned earrings, necklaces, rings, and other jewelry, and they are the traditional gift for a 40th wedding anniversary.

Chemically, a ruby is an aluminum oxide. Rubies get their color from traces of chromium. The red of most rubies has a brownish or yellowish tint. The rarest, most highly prized rubies are pure “pigeon-blood red.” Rubies and sapphires are second only to diamonds in hardness, and fine-quality rubies are among the costliest of all gems. The finest rubies come from Myanmar. Other primary producers of rubies are Cambodia, Kenya, Madagascar, Tanzania, Thailand, and Zimbabwe.

A star ruby cabochon shows a six-rayed star within it when seen in a bright light. A cabochon is a rounded, polished stone. The largest known natural ruby, named the “Eminent Star,” weighs 6,465 carats, or almost three pounds (1.36 kilograms). Millions of carats of inexpensive synthetic rubies are made each year. But a demand for real gems has allowed the natural stones to maintain their high value. It can be hard to distinguish between natural and synthetic rubies, even for experts. Experts are also challenged when determining whether the color of a natural ruby has been improved by heating.

April 24, 2019

If your birthday is in April, your birthstone—the gem associated with the month of your birth—is the diamond. The diamond is the hardest naturally occurring mineral, and also one of the most valuable natural substances. Because of its hardness, the diamond is the most lasting of all gemstones. In Europe, Japan, and North America, diamonds are widely used in engagement and wedding rings. Diamonds are also used in industry for cutting, grinding, and boring other hard materials. About half of the world’s natural diamonds are suitable only for industrial use. A small percentage are set in jewelry.

This photograph shows a naturally occurring diamond embedded in a sample of the rock kimberlite. Diamonds may be mined from pipe-shaped deposits of kimberlite, which fill the throats of extinct volcanoes. Natural diamonds are dull and must be cut by skilled jewelers to bring out the gem’s distinctive sparkle. Credit: © Matteo Chinellato, ChinellatoPhoto/Exactostock/SuperStock

Diamonds have been treasured at least since the days of the ancient Roman naturalist Pliny the Elder. He wrote: “Diamond is the most valuable, not only of precious stones, but of all things in the world.” Trade in diamonds was also prevalent in ancient India, and by the Middle Ages diamonds were fashionable accessories in several parts of the world. The diamond is a traditional birthstone for Aries (March 21-April 19), a sign of the zodiac. It is also a traditional gem gift for a 60th wedding anniversary—an event also called a diamond anniversary. In the past, some people believed diamonds possessed magical powers. According to legend, wearing a diamond could relieve fatigue or cure mental illness.

Diamonds are crystals that are made up almost entirely of carbon. Some diamond crystals have six faces, but most form octahedrons,which have eight faces. Natural diamonds probably form in Earth’s upper mantle—the zone beneath the crust—where high temperature and pressure cause carbon to crystallize. Diamonds are later brought to Earth’s surface by volcanic activity. The gems can be found in several places around the world, but the leading producers of natural diamonds include Australia, Botswana, Canada, the Democratic Republic of the Congo, and Russia.

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Birthstones, according to tradition, bring good luck when worn by a person born in the associated month. Credit: WORLD BOOK illustrations by Paul D. Turnbaugh

According to tradition, a birthstone brings good luck to a person born in its month. Each birthstone also corresponds to a sign of the zodiac. The belief in birthstones may have come from a Bible story about Aaron, the first high priest of the Israelites. The story describes Aaron’s breastplate, which was decorated with 12 precious stones. Early writers linked these stones with the 12 months of the year and the 12 signs of the zodiac. The custom of wearing a stone that represented a person’s zodiac sign probably originated in Germany or Poland in the 1700′s.

March 11, 2019

If your birthday is in March, you have two birthstones (gems associated with the month of your birth): aquamarine and bloodstone (a variety of chalcedony). Aquamarine is a light blue or bluish-green gem. It is cut in facets (polished flat surfaces) and used in all types of jewelry. Bloodstone is a dark green gem with red spots. It too is used in jewelry, but it is also associated with Christianity.

Aquamarine is one of two birthstones for the month of March. Credit: © Albert Russ, Shutterstock

Aquamarine is a variety of the mineral beryl. The most popular color is a clear sky-blue. Aquamarine is often treated with heat to improve its color. Almost all aquamarine is transparent. Aquamarines have been known since ancient times, when legends said the gems could help people relax or could act as an antidote to poison. The ancient Romans believed the gem could cure laziness and produce courage. The most important source of aquamarines is Brazil.

Bloodstone is another birthstone of March.
Credit: © Shutterstock

Bloodstone, a variety of the mineral Chalcedony, is related to agate, carnelian, and onyx. Chalcedony was named for the ancient town of Chalcedon, in what is now Turkey, which is near deposits of the mineral. Bloodstone is sometimes called Martyr’s Stone or Christ’s Stone because legend attributed the gem’s red spots to the blood of Jesus Christ. The ancient Greeks called bloodstone heliotrope (also a type of flower) for the way it reflects light. The Babylonians used bloodstone to make amulets, decorative vessels, and seals.

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Birthstones, according to tradition, bring good luck when worn by a person born in the associated month. Credit: WORLD BOOK illustrations by Paul D. Turnbaugh

According to tradition, a birthstone brings good luck to a person born in its month. Each birthstone also corresponds to a sign of the zodiac. The belief in birthstones may have come from a Bible story about Aaron, the first high priest of the Israelites. The story describes Aaron’s breastplate, which was decorated with 12 precious stones. Early writers linked these stones with the 12 months of the year and the 12 signs of the zodiac. The custom of wearing a stone that represented a person’s zodiac sign probably originated in Germany or Poland in the 1700′s.

February 8, 2019

If your birthday is in February, your birthstone—the gem associated with the month of your birth—is the amethyst. Amethyst is a purple or bluish-violet gem. It is used to make rings, necklaces, brooches, and other jewelry. Amethyst is a variety of quartz. The purple color of amethyst is believed to be caused by impurities such as iron and manganese. Amethyst has been a prized gem since the days of ancient Egypt, and today it can be found among the British royal family’s crown jewels.

Amethyst is February’s birthstone.
Credit: © Sebastian Janicki, Shutterstock

Amethyst is the birthstone for Pisces (February 19-March 20), a sign of the zodiac. It is also a traditional gem for the 6th and 17th wedding anniversaries. In the past, some people believed amethyst possessed magical powers. According to legend, wearing an amethyst could increase your intelligence or rid your mind of evil thoughts. The wine-colored gem could even prevent a person from becoming drunk (on too much wine, of course). Amethyst most often appears as crystals lining cavities in volcanic rock. It can be found in several places around the world, but the major sources for amethyst are Brazil and Uruguay in South America.

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Birthstones, according to tradition, bring good luck when worn by a person born in the associated month. Credit: WORLD BOOK illustrations by Paul D. Turnbaugh

According to tradition, a birthstone brings good luck to a person born in its month. Each birthstone also corresponds to a sign of the zodiac. The belief in birthstones may have come from a Bible story about Aaron, the first high priest of the Israelites. The story describes Aaron’s breastplate, which was decorated with 12 precious stones. Early writers linked these stones with the 12 months of the year and the 12 signs of the zodiac. The custom of wearing a stone that represented a person’s zodiac sign probably originated in Germany or Poland in the 1700′s.

January 4, 2019

Is your birthday in January? If it is, do you know your birthstone—the gem associated with the month of your birth? For January, it is the garnet, a reddish-brown gem that is part of a group of hard, glassy minerals. Garnets were one of the most popular decorative gems of ancient Rome, and were often inlaid in gold bracelets, earrings, and other ornamental items.

January’s birthstone is the garnet, a hard, glassy mineral that is sometimes used in making jewelry. Credit: © Luca 85/Shutterstock

According to tradition, a birthstone brings good luck to a person born in its month. Each birthstone also corresponds to a sign of the zodiac. The belief in birthstones may have come from a Bible story about Aaron, the first high priest of the Israelites. The story describes Aaron’s breastplate, which was decorated with 12 precious stones. Early writers linked these stones with the 12 months of the year and the 12 signs of the zodiac. The custom of wearing a stone that represented a person’s zodiac sign probably originated in Germany or Poland in the 1700′s.

Garnets include six major types of silicate minerals: almandine, andradite, grossularite, pyrope, spessartite, and uvarovite. Garnets are composed of silica and such elements as aluminum, calcium, iron, magnesium, and manganese. They range in color from red, brown, and black to various shades of yellow and green. Crystals of garnet are found in all types of rock, but chiefly in metamorphic varieties.

Some garnet crystals are used in making jewelry. Red garnet, a gem-quality garnet, commonly includes a mixture of almandine and pyrope. Garnets are also used as abrasives for grinding and polishing. Garnets are found throughout the world. Those of gem quality are mined chiefly in central Europe, Russia, and South Africa.