Thursday, March 13, 2008

Gemstone Basic - Gemstones from Amethyst to Zircon

Amethyst

The brilliant purple stone known as amethyst is draped in centuries of history – and mystery. Purple is the traditional color of royalty and amethyst has been used in the British Crown Jewels, by Egyptian royalty, and in Tibetan Buddhist prayer beads. The name comes from the Greek word “amethustos” which means “not drunken,” and the amethyst was thought to prevent one from becoming intoxicated from wine.

Famed renaissance genius Leonardo Da Vinci claimed amethyst was capable of warding off evil thoughts and could inspire intelligence.

Later the amethyst became a symbol of celibacy, piety and religious purity and thus was adopted as a Catholic symbol around the time of the Middle Ages. Amethyst came to be the stone of Bishops and some Bishops still wear amethyst rings.

Actually purple quartz, Amethyst is the birthstone for February. Amethyst is primarily mined in Brazil and Zambia, but is also found in Russia, Mexico, Sri Lanka, and in the US it’s found in New Mexico.

Diamond

Without a doubt the diamond is by far the most highly prized and valuable of gemstones. Most diamonds will never be bound for a jewelry store. They are used for industrial applications like the making of cutting tools and polishing equipment. The power of the diamond’s beauty is undeniable and that is why we tend to give diamonds for the most special of occasions – an engagement, a wedding, a 30-year anniversary.

Diamonds are made of carbon atoms that are bonded together in four directions yielding the hardest naturally-occurring substance on earth. The conditions under which diamonds are formed are extreme to say the least. To pack carbon atoms so tightly, it is thought that diamonds were created deep below the earth’s surface where pressures are up to 65,000 times that of the atmosphere at the earth’s surface. Extreme temperatures are also necessary for diamonds to form – about 2,700 degrees Fahrenheit.

During these conditions it’s not uncommon for a few stray, non-carbon atoms to sneak in. If nitrogen makes its way in the result will be a yellowish, less desirable diamond. However, if a little boron is present, the diamond may take on a bluish tint which is very rare and therefore highly prized.

April’s birthstone, Diamonds are thought to have first been discovered in ancient India when they washed forth from the ground after heavy rainstorms. Diamonds have since been found all over the globe in Brazil, Siberia, South Africa, and even the US and Canada. Today most gem-quality diamonds are found in parts of Africa.

Emerald



Perhaps because of its stunning green color the emerald for centuries has symbolized life and rebirth. The pharaohs of Egypt mined emeralds as far back as 3,000 BC. The Incas and Aztecs also mined emeralds – and some of the best emeralds are still found in South America. The emerald is the most highly sought of the gemstone family known as beryl, of which aquamarine is also a part.

The emerald’s green color is caused by the presence of chromium in a particular form of beryl. Like diamonds, emeralds have inclusions – usually in the form of tiny gas or liquid bubbles, stress fractures, and trace amounts of foreign crystallizations. These internal inclusions are called “jarden” – the French word for garden – and contribute to the emerald’s rich green coloration.

Emeralds tend to be found in Columbia, Brazil, Zambia, Zimbabwe, Pakistan, and Russia. Emeralds are May’s birthstone.

Garnet

Garnet is actually a family of gemstones. The word garnet is again derived from a Greek word – in this case “granatum” which refers to the pomegranate seed.

When one thinks of garnet variations of the color red almost always leap to mind. The truth is garnet is found in a wide variety of colors and intensities. But the most common garnets are the reddish ones and they are called by a number of specific names including Almandite, Rhodolite, and Pyrope. These stones range in color from a medium reddish orange to a purplish red or reddish purple.

Other types of garnet include Malaia (pinkish orange hues), Spessartite (yellowish orange) and Tsvorite (green tones). Some garnets are known as color change garnets due to their tendency to shift color depending upon how the light strikes them.

Garnet is the birthstone of January and its various types are found throughout Europe, Asia, Africa, and the Americas.

Opal

The opal probably owes its name to the Sanskrit word “upala” which means “valuable stone.” Australia is the center of the known opal universe and the opal plays a significant role in the traditional folklore of Australia’s Aboriginal people. Today almost 90% of all gemstone opals come from the mines of Australia. The remaining amount is found in northern Brazil, Mexico and in Nevada and Idaho in the US. There are basically three types of opals with differing properties and values.

Precious opals

What distinguishes a precious opal is its opalescence – or the intense play of color as light dances on the stone’s background, or body-color. Varieties of precious opals include White (translucent with white body-color), Black (opaque with dark body-color), and Jelly (transparent with almost no play-of-color).
Fire opal

These opals are aptly named. Their unique appeal comes from a stone that has a red, yellow, or orange body-color, and is in the range of transparent to semitransparent. Sometimes there is the presence of opalescence – or play of color – and sometimes there is none. While most other opals are found in Australia, fire opals are primarily found in Mexico, and are sometimes called “Mexican Opals.”

Common opal


As the name might suggest, these opals are not all that rare. Common opals are for the most part opaque and there is little to no play of color.

While the sheer beauty of the opal inspires wonder and they are certainly here to be enjoyed, great care must be made to ensure opals maintain their luster and play of color. Opals contain small amounts of water and over time the water content in an opal can diminish, damaging its beauty and value. When buying opals, always make sure your jeweler has a gemologist available, and ask him or her about the proper care and storage of opals.

Pearls

Pearls are unique in the world of gemology as they are the only gem that is formed inside a living creature. Pearls are produced when an oyster defends itself from an invader, or irritant – like a tiny spec of sand or other debris. The oyster produces a substance called nacre which is deposited around the irritant. Over time the layers of nacre build up to produce a pearl.

The pearl was once one of the most prized treasures on earth because their production was a totally random, natural process. In the late 1800s a Japanese man named Kokichi Mikimoto learned he could gather oysters, implant them with an irritant, and return them to the water where they would produce a cultured pearl. The process usually takes about three years, but can take as many as six years. Today almost all pearls are cultured because natural sources have been depleted.

Cultured pearls generally fall into two categories – saltwater and freshwater. Japan is still the leading producer of saltwater cultured pearls. The largest saltwater pearls are cultivated in the South Pacific with Tahiti being the home of the highly prized Black Pearl. China is the leading supplier of freshwater pearls, they are also produced in the Mississippi river.

Like most other gemstones, pearls are valued by size, rarity, beauty, and degree of perfection. But two specific qualities are used to determine the value of pearls – orient and luster. Orient describes the degree of mild iridescence that results from light refracting off the layers of the nacre. Luster refers to the level of shine and reflectivity on the pearl’s surface. Pearls that have a slightly rose tint are very desirable. Other colors include hints of gray, green, lilac, gold, and of course, the Tahitian Black Pearl.

Unlike some other gemstones, it is simple to determine the authenticity of a pearl. Take the pearl and very gently rub it on the edge of a tooth. The feeling should be slightly abrasive. A completely glass-like smoothness is a sign that a “pearl” is probably just a painted glass bead. A real pearl, either cultured or natural, is the birthstone of June.

Ruby

The ruby likely gets its name from the Latin word “rubeus” which means red. The ruby is also often referred to as the “king of the gems,” not only because of their popularity among royaly, but also because the Sanskrit word for ruby, “ratnaraj,” literally translates to “King of gemstones.”

India is believed to be the traditional birthplace of ruby lore, and was for a long time a prime source for rubies. In fact rubies have been studied, admired, and mythologized in Indian literature for at least two-thousand years. Today rubies are chiefly mined in Southeast Asia, Thailand, Myanmar (Burma), Sri Lanka, and Africa. Other places where rubies are found include Cashmere, Nepal, Afghanistan, and Northern Pakistan.

Around 1800 scientists determined that rubies and sapphires belonged to the same family of minerals called corundum (this word is also rooted in the Sanskrit – “kuruvinda”). Up until this time, both red garnet and red spinel were often referred to as rubies. The differences are so subtle, many of the brilliant red gemstones in England’s Royal Jewels – thought for years to be rubies – turned out to be red spinels.

While the word ruby immediately conjures thoughts of the color red, the depth and intensity of red can vary considerably. For years the most highly-prized rubies had a deep red color which was referred to as “pigeon’s blood.” The redness of rubies can vary so dramatically from deposit to deposit, it is almost impossible to predict where the most desirable rubies will be found. The red color of the ruby is caused by the presence of chromium. The ruby is the birthstone for July.

Sapphire

The word sapphire comes from “Sappheiros” Greek word for blue. But blue is by no means the only color of sapphires. The gemstone that is almost synonymous with “blue” is also found in bluish green, brown, yellow, violet, pink, and the breath-taking and highly valuable pink-orange “padparadscha” – the Sinhalese word for lotus flower.

The sapphire belongs to the same family of minerals, corundum, as the ruby. Sapphires are found today in many of the same regions where rubies are found – largely due to their chemical similarities. Sapphires are currently mined in Sri Lanka, Australia, Africa, Thailand, and in Montana.
The most valuable sapphires are the deep blue Kashmir stones – so named for the region in India where they were originally found. Nearly as precious are sapphires from Myanmar (Burma).

Another extremely rare and valuable variety of sapphire is that which contains what is called an “asterism.” The asterism is a naturally occurring trait caused by slivery inclusions that appear as a six-pointed star floating in the heart of the stone when the light catches it just right. These sapphires depend on the skill of the gem cutter as much they do on nature for their singular beauty, and the craftsman must cut the stone into domed shape called a “cabochon.”

For centuries, because of its true-blue color, the sapphire has been a symbol of sympathy, harmony, loyalty, permanence, and reliability. For this reason in some cultures the sapphire is a popular stone for engagement rings. The sapphire is the birthstone for those born in September.

Topaz




The origin of the word topaz is likely the island of Topazios in the Red Sea – a theory partially substantiated by the fact that ancient Egyptians associated the golden color of topaz with their sun god Ra. The Romans also symbolized their sun god, Jupiter, with topaz.

Today the topaz is most commonly thought of as having a brilliant blue color. In reality the topaz, like a number of other precious stones, occurs in a variety of colors including yellow, reddish-brown, pale green, and even colorless. Topaz can have a gold or amber color – hence the sun god meanings for the Egyptians and the Romans. “Imperial” topaz, so named for the Russian Czars who prized it, possesses an orange coloration with hints of pinkish red. Imperial topaz is among the world finest. Pink topaz is also one of the most valuable varieties.

Chicanery lead the U.S. Federal Trade Commission to regulate the nomenclature in the world of gemstones – sapphires in particular had been the subject of creative marketing language. “Smoky Topaz” is really quartz and it is now called “smoky quartz.” “Golden topaz” is actually heat-treated amethyst. Mix-ups and misrepresentations have lead to real topaz being called “precious topaz.” Topaz is the traditional birthstone for November, but because blue topaz is prevalent and inexpensive, it is a widely accepted substitute for March’s birthstone aquamarine.

Zircon

Zircon probably gets its name from the Persian word “Zargun” with “zar” meaning “gold” and “gun” meaning “color.” While sometimes the zircon has been viewed as a second-class citizen in the gem world, it is a brilliant, fiery gemstone. In medieval times it was believed the zircon possessed mystical properties that could remedy sleeplessness, promote wealth, and endow its owner with wisdom and honor.

Like many other gemstones, the zircon appears in myriad colors, the most sought after being red. Blue zircons are also highly-valued. Other colors include brown, yellow, colorless, and orange. Zircons are often heat-treated to achieve a blue, golden-brown, or colorless appearance. Of all gemstones, clear zircons most closely resemble diamonds, but that is where the similarities end. Zircons are downright brittle compared to diamonds, and therefore greater care should be taken with them.

Zircons are mined in a number of countries but most are found in Australia, Cambodia, Myanmar, Sri Lanka, and Thailand. Blue zircon is the birthstone of December, but turquoise and tanzanite are accepted alternatives.

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