Mohs scale hardness: 5-6
There are three birthstones for those who born in December; turquoise, zircon and lapis lazuli, but the most popular one is turquoise which also the accepted gem for the 5th and 11th wedding anniversaries. Turquoise is one of the oldest known gemstone. The word “turquoise” is derived from the French, which means “Turkey stone”, for it originally was thought to be a product of Turkey. Turquoises do not occur in Turkey but was traded at Turkish bazaars to Venetian merchants who brought it to Europe. The finest turquoises are found in Iran although is challenged by American Southwest.
How Turquoise is Formed
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.
The color of turquoise normally will only stable if the gem is not exposed to high temperature, strong light, oil, cosmetics, perspiration and household chemicals. The most desired sky-blue color of turquoise will change at 482 degrees F (250 degrees C) into a dull green. If the stone lose its natural water content (18-20%) will result in undesirable color-changes as well.
Because turquoises are fragile, just slightly stronger than window glass so special care must be taken. Turquoises are also easily disturbed by heat, oil, sunlight, moisture, perspiration, dryness so they should not come in contact with strong perfumes, or chemicals. This is because of their porosity so they easily absorb dirt, grease and smell for long period.
In order to produce a harder turquoise, the stone is often dyed and stabilized with resins to retains its polish and color (it does not change its hardness). Color-improvements can be gained with paraffin or oil, or other color agents like Berliner blue, copper salt or aniline colors. Reconstituted turquoise is made from small chips andd "chalk" to which dyes and plastic resin is added.
Stabilized turquoise is best recognized by its transparent plastic appearance. It is too easy to be scratched with a hard knife blade while high quality turquoise cannot be scratched with a knife. High quality turquoise cannot be stabilized or treated as the plastic will not penetrate compact dense material. Treated turquoise is a turquoise that has been stabilized and also dyed. It should be priced much less than stabilized or natural turquoise. Reconstituted turquoise is a low grade turquoise which has been groundd to powder, saturated with epoxy resin, dyed, compressed into blocks and then cut (it should be very inexpensive).
The most important considerations in terms of value is the evenness and saturation of the color, followed closely by how compact is the material and its capability of taking a good polish without stabilization.
Turquoise Healing Powers and Properties
Turquoises need to "breath" to conserve its deep natural color. Lack of air will eventually turn the stones greenish, contributing to them losing their value. Some are highly prized for their unique veins, like red-color to dark-red veins are believed to be sacred one and are widely looked for. According to occultist, turquoise stones are the only stone which can "die", a "dead" turquoise is veinless and is no more valuable. Turquoise has been used by kings and rulers of the past, in sculptural works, and has been fashioned into beads and pendants.
It is believed turquoise have special properties:
- Bring peace, luck, safety and happiness.
- To ward off unnatural death, the color changes if danger is approaching.
- Provides protection against evil.
- To promote mental and spiritual clarity to enhance trust, wisdom, kindness and understanding.
- Used as a goodluck charm.
- Can strengthen business relationship.
December birth flower: Poinsettia.
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