Birthstones for December

December has two birthstones, turquoise and zircon. Turquoise tends to form in veins of alumina-rich rocks of desert regions. The turquoise crystalizes in the veins of such rocks. The chemicals found in turquoise are derived from those leached out of adjacent rocks.

Turquoise ranges in colour from sky-blue to light greenish blue. It is a relatively soft gemstone and can be broken quite easily. Pure turquoise is opaque but it is almost always discoloured by surrounding chemicals. The sky-blue shade of turquoise comes from the presence of copper. Iron gives the mineral greener shades. 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. Only about ten percent of turquoise is gem quality.

Turquoise 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 the primary producers of turquoise. The only known occurrence of crystalized turquoise is in a copper mine in Virginia.

Lore says that Turquoise is a symbol of good fortune as well as to bring success and wealth to those who wear it.

Turquoise is one of the earliest known gems to be used in jewelry. The Pharaohs of ancient Egypt wore turquoise. When a tomb was excavated in 1900, it contained the mummy of Queen Zer, who ruled in 5500BC. She was wearing beautiful turquoise bracelets. Turquoise beads have been found in ancient Mesopotamia from 5000BC. Passages from the Koran were inscribed on pieces of turquoise and used as amulets in the 7th century AD. Perhaps some of the best known turquoise jewelry came from the Inca of ancient Peru who crafted beads and figurines from it.

Our European ancestors believed that turquoise was a love charm. Shakespeare mentioned turquoise in the merchant of Venice. The idea traveled to Russia where it was popularly used in wedding rings.

But nowhere is turquoise as popular as it is to the Native Americans of the Southwest US. The Navaho,Hopi, Zuni and Pueblo nations have used the gem to create incredibly beautiful pieces of jewelry for over a thousand years. There, turquoise is called "Chal-cui-hui-tal", which means "the highest and most valued thing in the world". Today the artists make necklaces, pendants, earrings and even use it to decorate carved silver boxes. Artists use the blue turquoise to symbolize the heavens and the greenish shades to symbolize the Earth.

Turquoise also plays an important part in the spiritual lives of these Southwest tribes. The Navajo believed that turquoise pieces, thrown into a river while offering a prayer to the rain god, would bring much needed rain.

There is no shortage of superstitions connected with turquoise. If a man owned a gem which changed colour (as turquoise can do when it loses water,) he believed it meant his wife was unfaithful. Persians said that the reflection of the new moon on a turquoise stone brought good luck, and guarded against evil. In 15th century Europe, it was believed that turquoise could monitor the owner's health, turning pale if the owner fell ill and losing colour in death. Good health was indicated by a brilliant colour.

The second birthstone for December is Zircon. Its name is probably derived from the Arabic words "zar" and "gun", meaning "gold" and "color". Zircon comes in a wide variety of colours but all of them are brilliant.

Zircon is a common minor accessory of granitic rocks and occasionally in metamorphosed limestones. It is also often found as a residual heavy mineral in sands and gravels. Zircon is always found as a crystal, sometimes an inch or more across. Even larger ones have been found in Canada and Australia.

In its natural form, Zircon ranges from colourless to pale yellow or green. The colours are caused by tiny amounts of thorium and uranium which replaces zircon in the crystal structure. Over geologic time Zircon changes. The uranium and thorium inclusions emit radiation that alters the original crystal structure, producing a glass-like material with colours of red to brown, orange and yellow.

Gem quality zircon is fairly rare. These form most often in pegmatites and in fissures. Due to weathering of the gem-bearing rocks, most zircon gems are found in alluvial and beach deposits.

Humans have also altered zircon. A new blue colour, called "starlight blue," was created by heating golden brown or yellow zircon in the 1920s. Plain brownish zircon was heated in an oxygen free environment which turned the gems into brilliant blue stones. Originally the gems were passed off as a new gemstone but the trickery was soon uncovered. Nevertheless, it was still a popular gem.

The rarest zircon is the red gemstone. Next in value is the pure blue and sky blue variety. Least expensive are the colourless, yellowish and brown types.

Colourless zircons are the best imitators of diamonds in the world. But that is in appearance only. Zircon is quite a brittle stone and can be easily broken due to internal stresses in the crystal caused by radiation damage and heat treatment.

Zircon is found in alluvial deposits in Thailand, Cambodia, and the northern part of Vietnam. Bangkok is a major center for processing zircons. Sri Lanka is well known for a colourless variety of zircon called the Matura diamond. Smaller deposits can be found in Australia, Canada, Burma and Norway.

Ancient Arabs favored reddish-brown and orange varieties of zircon, and they were even mentioned in the classic book "Arabian Nights." Ancient Hindus used green zircon among the stones of the Kalpa Tree, where it represented the leaves of the tree. This tree was a symbolic offering to the gods.

Travelers used zircon in amulets to protect them from disease and harm. It was also believed to ensure good relations with whomever the traveler met along his way. Some believed zircon would chase away 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.

Even today, some believe zircon has healing powers and can be used to induce sleep.

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