Understanding Gem Jewelry

Chemically speaking, tourmaline is a complex aluminum and boron silicate mineral. Colors are red, pink, blue, green, yellow, violet, and black; sometimes it is colorless. Two or more colors, arranged in zones or bands with sharp boundaries, may occur in the same stone. Tourmalines are found in pegmatite veins in granites, gneisses, schists, and crystalline limestone. Important sources include Elba, Brazil, Russia, Sri Lanka, and parts of the U.S. Tourmaline scores a 7.0 on the Mohs scale.

Tourmaline occurs in every color of the rainbow and combinations of two or three colors. Bicolor and tricolor tourmalines, with bands of colors are very popular. Sometimes the colors are at different ends of the crystal and sometimes there is one color in the heart of the crystal and another around the outside. One color combination, pink center with a green rind, is called "watermelon tourmaline" (seedless, of course!) Sometimes designers set slices of the crystal instead of faceted stones to show off this phenomenon.

Almost every color of tourmaline can be found in Brazil, especially in Minas Gerais and Bahia. Pink and green colors are particularly popular. In 1989, miners discovered tourmaline unlike any that had ever been seen before. The new type of tourmaline, which soon became known as Paraiba tourmaline, came in incredibly vivid blues and greens. The demand and excitement for this new material, which soon fetched more than $10,000 per carat, earned more respect for the other colors of tourmaline.

Pink and green tourmaline are now widely available and are especially popular in designer jewelry. Blue tourmalines are also very much in demand but the supply is more limited. Rubellite tourmalines, which come in a ruby red color, are very popular as ruby alternatives.

Tourmalines are most often cut in long rectangular shapes because of their long and narrow crystal shape. Tourmaline crystals are beautiful, pencil thin and ridged, and they are also sometimes set in jewelry. Some designers also set rainbows of tourmaline in each color of the spectrum. Tourmaline is strongly pleochroic: the darkest color is always seen looking down the axis of the crystal.

In addition to Brazil, tourmaline is also mined in Tanzania, Kenya, Madagascar, Mozambique, Namibia, Afghanistan, Pakistan, Sri Lanka, and California and Maine in the United States. Maine produces beautiful sherbet colors of tourmaline and spectacular minty greens. California is known for perfect pinks, as well as beautiful bicolors.

One particularly beautiful variety is chrome tourmaline, a rare type of tourmaline from Tanzania which occurs in a very rich green color caused by chromium, the same element which causes the green in emerald. Tourmaline is a hard and durable gemstone which can withstand years of wear.

Gemstone colors

Emerald - The greenest of the green, emeralds were cherished by the Romans above all other gems. Find out what makes this favorite of Cleopatra's so unique

Garnet - January's birthstone is famous for being as red as a ruby, but this colorful gem actually comes in every color but blue. Discover this elusive chameleon

Opal - Opals are the gem world's silvery mirrors, reflecting back every color in a flash of pastels or a streak of fire. Uncover this enchanting stone.

Peridot - Peridot is a gem that gets around. From ancient Egypt to present-day Apache mesas, even in space meteorites--you never know where its green gleam is going to show up.

Ruby - The color of courage and blood, rubies are even more precious per carat than diamonds. See why the Biblical authors to modern collectors use them as the measure of ultimate value.

Tanzanite- Millions of years in the making, deep-violet tanzanite revealed itself to humans only thirty years ago. Read about this newest discovery.

Sapphire - Blue as the perfect sky, sapphires have been used as protective talismans for centuries. Learn about the versatility of this stone that combines hardness and color variation like no other.

Tourmaline - Available in every color and saturation, this tough crystal has become a popular substitute for rubies, emeralds, and sapphires. Unmask this clever chameleon.

Turquoise - The lovely opaque blue of turquoise is produced by traces of copper in the stone. Elements of iron will also create a pretty, pronounced green hue. Oxides contribute to the stone's famous gray, brown or black veining.