December Birthstone

December Gemstone: Blue Topaz, Turquoise
December Birthstone Color: Blue 

As cool and inviting as a blue lake on a blistering summer day, December's birthstone is derived from the Sanskrit word "tapas," meaning fire.  This is because Blue Topaz was considered by ancient civilizations to have cooling properties.  Not only was it believed to cool boiling water when thrown into the pot, but to calm hot tempers as well!  This gemstone was credited with many other healing powers, among them the ability to cure insanity, asthma, weak vision and insomnia.  The Blue Topaz was even thought to have magical properties in its ability to make its wearer invisible in a threatening situation. 
Blue Topaz is the hardest of the silicate minerals.  While pure Topaz is colorless, minor changes of elements within the stone result in a variety of other colors, such as blue, pale green, red, yellow and pink. 
The blue hue is created when Topaz is heated, whether the heat source is natural or engineered by man.  The three shades of Blue Topaz are Sky, Swiss and London Blue.  The latter is the deepest blue and is often used as a less expensive substitute for Sapphire. 
Topaz is found primarily in Brazil, Nigeria, Sri Lanka, Mexico, Pakistan, China, and the United States. 
A gift of Blue Topaz is symbolic of love and fidelity.  Luckily, this cool blue gemstone has no legendary power to put out the burning flame of love! 

Alternate

Turquoise is chemically a hydrated copper/aluminum phosphate, of aggregate, cryptocrystalline structure. Turquoise is formed, over a span of millions of years, it occurs by chemical reaction when water leaks through rocks which containn specific minerals such as alumunium and copper. The percentages of those variious minerals in the rock dictate the gemstone’s shade. They are found as an opaque deposit in veins, or nodules within host rocks, or as shallow crusts on the surrface of rocks. In general, a high proportion of silicate minerals decreases the porosity of the stone and increases hardness, while a high content of clay minerals, give the opposite effect.

The gems are mostly mixed together with black, dark gray or brown veins of other minerals or of the hosting rock (like opal or chalcedony, brown limonite, white kaolinite or black chert). Those stones are called Turquoise matrix. Other minerals like chrysocolla have been used to imitate turquoise.

Turquoise is found in many different forms: turquoise deposited in cracks in rocks (vein turquoise), turquoise formed as nuggets, turquoise formed in a cavity lined with quartz crystals, and turquoise formed in cracks in rock to form disc-shaped or flattened nuggets. They are generally form in arid climates such as the American Southwest.

Spider web turquoise is made up of small nuggets cemented togeher with natural rock or matrix. Most mines produce some spider web turquoise. When cut through, its aggregate mass of nuggets resembles spider web.

Sea form turquoise is a descriptive term applied to a kind of knobby, foam-looking nugget tthat can be polished without cutting, except for flatening the back to mount in jewelry. It has not been popular until the term "Sea Foam" appealed to the buyer.

Colors of Turquoise

Turquoises are one of the most valuable non-transparent minerals, the color ranges from light green to dark green, light blue to dark blue or mixed between the two colors. Most of turquoises are green in color but blue turquoises are more valuable. Variations in color are due to the presence of metals, such as copper impurities in the case of blue turquoise, chromium or vanadium impurities in the case of green turquoise and iron impurities for yellow turquoise. There are also rare specimens of blue-violet color, which contain strontium impurities.