Turqouise – December’s primary birthstone. Turquoise is considered by some to be a symbol of good fortune and success, believed to bring prosperity to its wearer. It’s 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.
Enhancements – Pale and chalky varieties are sometimes impregnated with oil, paraffin, liquid plastic and glycerin to give it a good polish.
Zircon – 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. 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.
Enhancements – Pale and chalky varieties are sometimes impregnated with oil, paraffin, liquid plastic and glycerin to give it a good polish.