Turquoise

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December's birthstone, turquoise was among the first gemstones ever mined. Stunning sky blues to stimulating sea greens have made turquoise one of the most popular color trends in jewelry history. Copper gives turquoise its range of blue hues while iron is responsible for its green colors. Treasured since the days of ancient Egypt, and the thousands of years since, turquoise is said to bring good fortune and happiness to those who wear it.

Turquoise Polished
Turquoise Classification
Common Name Turquoise
Species Turquoise
Turquoise Optical Properties
Transparency Semitranslucent - Opaque
Dispersion Strength: None
Refractive Index 1.610-1.650
Birefringence 0.04
Optic Character Biaxial
Optic Sign Positive
Polariscope Reaction Aggregate (AGG)
Fluorescence SWUV: Inert
LWUV: Inert to weak greenish yellow
CCF Reaction None
Pleochroism None
Turquoise Characteristic Physical Properties
Hardness 5-6
Streak White
Specific Gravity 2.380-2.860 Typical:2.740
Toughness Varies
Inclusions Turquoise often has brown, gray or black matrix that is sometimes recessed below the polished surface of the stone. Stone may contain pyrite or calcite inclusions.
Luster Vitreous, Waxy
Fracture Granular, Conchoidal
Cleavage None
Turquoise Chemistry & Crystallography
Chemical Name hydrated copper aluminum phosphate
Chemical Formula CuAl6(PO4)4(OH)8-5H2O
Crystal System Triclinic
Chemistry Classification Phosphate

Turquoise Colors

  • Green Turquoise Green
  • Blue Turquoise Blue

Turquoise Spectra

Turquoise Spectra
TURQUOISE

Color due to copper. The diagnostic lines due to copper in the deep blue to violet region are difficult to detect and have eluded many observers. Light reflected off the sub-surface provides insufficient absorption. Transmitted light through a translucent edge, although, better is not always possible. This shallow cabochon did however transmit sufficient light at the edge to show an absorption band centered at 425nm. with just a hint of transmission in the middle to indicate two lines. (See BLC0973 below) The remainder of the spectrum transmits to about 530nm. before total absorption take over.

Turquoise Spectra
TURQUOISE

Color due to copper. The very small shallow cabochon used for this spectrum was thin enough to pass sufficient light by direct transmission. This photograph has been over exposed using a 150 watt fiber optic lamp so that the viewer can easily resolve the two lines at 420nm. and 432nm. As a result, the remainder of the spectrum transmits to about 560nm.

Jewelry Television acknowledges the significant scientific contributions of John S Harris, FGA to the study of gemstone spectra and with deep appreciation to him, acknowledges the use of his images and related notes about gemstones and their spectra in the educational materials on this website.

Alternate Names

Turuqois, Gilson Synthetic Turquoise, Gilson Turquoise

Countries of Origin

Tanzania, United Republic Of; Colombia; Iran (Islamic Republic of); United States of America (the); Cambodia; Ukraine; Thailand; India; Canada; Unknown; China; Brazil; Italy; Mexico; Israel; Philippines (the); Chile; United Kingdom of Great Britain and Northern Ireland (the)

History

Stunning sky blues, striking sea greens and rich robin's egg shades make turquoise a very desirable gemstone. Turquoise is almost always cut en cabochon or as a bead. It is seldom faceted. The dark and sometimes coppery-colored veins are part of the beauty of turquoise and the smooth cabochon cut serves to showcase these distinctive features. Turquoise may be the first stone ever mined. There is some evidence that suggests it may have been mined as far back as 4000 B.C. It is a 5 - 6 on the scale of hardness, but its porosity presented real challenges in the past, as turquoise changed color with time and wear. Today's gemstone treatments help alleviate that problem. The name, "turquoise," is relatively new to this blue stone. Pliny the Elder referred to it as callais from the Greek meaning "beautiful stone." It's thought that the name turquoise came into use somewhere around the 13th century.

Care

Gentle care, natural turquoise is very soft and porous, so avoid contact with oils and colored fluids. Clean with clean damp cloth only. Avoid hot water, household chemicals, steam and ultrasonic cleaners for stabilized stones.

Shop Turquoise

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Creation Classification

Lab Created

Some gems, like turquoise, are highly coveted but rare to find, much less in the sizes and quality people dream of owning. Laboratory created jewels offer you the best of both worlds. You get the beauty of a beloved gemstone, but at a budget friendly price. The term synthetic refers to a man-made material with a natural counterpart. The synthetic material replicates the chemical, optical and physical properties of the natural version with little or no variation.

Lab Created Turquoise
Lab Created Classification
Common Name Lab Created
Lab Created Optical Properties
Refractive Index 1.61-1.65
Lab Created Characteristic Physical properties
Specific Gravity 2.38
Inclusions Synthetic turquoise has tiny blue microspheres that give it a "cream-of-wheat" appearance. Stones might have blue thread like inclusions and artificial black matrix that is even with the surface.

Enhancement

Impregnated Turquoise

As it occurs naturally, turquoise is a soft mineral that is easily scratched. Its porous nature can allow the absorption of oils and fluids that can discolor it over time. To improve its durability and appearance, much of the turquoise on the market today is stabilized. One popular method of stabilization is impregnation, which fills the porous areas with a colorless agent, usually plastic.

Impregnated Turquoise Turquoise
Impregnated Turquoise Classification
Common Name Impregnated Turquoise
Impregnated Turquoise Optical Properties
Refractive Index 1.6-1.61
Impregnated Turquoise Characteristic Physical properties
Specific Gravity 2.5
Inclusions Impregnated turquoise often has brown, gray or black matrix that is recessed below polished surface.Stones will have a higher luster than natural turquoise. Stones may contain pyrite or calcite inclusions. Stones can have a speckled appearance similar to the "cream-of-wheat" effect if wax impregnated.
Tim Matthews

Author

Tim Matthews

Tim Matthews is President and Chief Executive Officer of Jewelry Television® (JTV), as well as a member of the company's Board of Directors. He oversees and leads all aspects of the company's powerful omni-digital retail platform that uniquely specializes in fine jewelry and gemstones. His passion for business and gemstones has led him to become a recognized expert in the field of gemology. He is a life member of the Gemmological Association of Great Britain (Gem-A) and has earned Gem-A's highest degrees, the Gemmology (FGA) and Diamond (DGA) diplomas. He is also a Graduate Gemologist (GG) of the Gemological Institute of America (GIA) and has also completed GIA's Graduate Diplomas in Diamonds, Colored Stones and Pearls. Under his leadership, JTV has become the leader in the sourcing and selling of color gemstones and jewelry.

This page was created on June 27, 2014.

This page was last edited on October 24, 2019.