Turquoise stone

The intense blue color in this rough is due to the presence of copper.

Turquoise

Turquoise is one of the oldest known gem materials. Turquoise is a copper ore found in arid or semiarid regions. The earliest turquoise mines were in the Sinai. In the el-Qaa region archeologists have found turquoise in tombs that are believed to date to 5000 B.C.. Turquoise jewelry and objects for ornamentation have been found in Egyptian, Persian, Chinese and Aztec historic sites. Native Americans in the Southwest United States have a long history of using turquoise in jewelry. Turquoise mining in what is known as the United States dates back to 200 B.C.. Vast historic trade routes can be traced from the American Southwest into Mesoamerica. Turquoise can be blue or green depending on copper, iron, and zinc content.

General Information

• Classification
• Optical Properties
• Characteristic Physical Properties
• Chemistry and Crystallography

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.

Turquoise Colors

Turquoise Spectra

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.

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.

We acknowledge 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); Cambodia; Philippines; United States of America; Ukraine; Thailand; United Kingdom of Great Britain and Northern Ireland; India; Canada; Unknown; China; Brazil; Italy; Mexico; Israel; Chile

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.

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.

Turquoise

Azure sky, robin’s egg blue: Vivid shades of turquoise define the color that’s named after this gem.

This turquoise is cut in a cabochon: the most common shape.

The preferred color for turquoise is a pure sky blue.

Some buyers prefer the presence of matrix in fashioned turquoise.

Turquoise is an aggregate of microscopic crystals that form a solid mass.

The intense blue color in this rough is due to the presence of copper.

Veins of matrix in this turquoise are remnants of its surrounding rock.

Overview

About Turquoise

Turquoise is found in only a few places on earth: dry and barren regions where acidic, copper-rich groundwater seeps downward and reacts with minerals that contain phosphorus and aluminum. The result of this sedimentary process is a porous, semitranslucent to opaque compound of hydrated copper and aluminum phosphate.

Birthstones and Anniversaries

Turquoise is the traditional birthstone for the month of December and the gem of the 11th anniversary.

4,000 BC

Turquoise buried in Ancient Egyptian tombs is among the world’s oldest jewelry.

Mefkat

Ancient Egyptians called turquoise “mefkat,” which also means “joy” and “delight.”

1519

Montezuma, thinking Cortes was Quetzalcoatl, gave him the god’s favorite gem: turquoise.

Facts

Treatments

There are a number of processes used to alter the color, apparent clarity, or improve the durability of gems.

Synthetics

Some gemstones have synthetic counterparts that have essentially the same chemical, physical, and optical properties, but are grown by man in a laboratory.

Imitations

Any gem can be imitated—sometimes by manmade materials or by natural materials chosen by man to impersonate a particular gem.

Why We Love This Gemstone

Spiderweb

The spiderweb of veins that appear in turquoise are matrix: evidence of the surrounding rock.

Legacy

A legacy of turquoise appreciation spans the globe, from ancient Egypt to Mesoamerica to China.

Copper

Turquoise is colored by copper, which creates some of the most vivid blues and greens in gems.

Quality Factors

Turquoise is judged on its color, texture, and the absence of matrix.

Color

The even blue color of this cabochon would be called Persian blue in the trade.

Clarity

These free-form turquoise cabochons show a typical matrix pattern.

Cut

Although turquoise is usually cut into beads and cabochons, it can also be carved.

Carat Weight

Cutters work around large areas of matrix to yield pieces of evenly colored turquoise.

Turquoise Quality Factors: The Comprehensive Guide

Research

Explore sources, gemological research, and the role of gems in history.

Turquoise from Zhushan County, Hubei Province, China

Quanli Chen, Zuowei Yin, Lijian Qi, and Yan Xiong , Oct 24, 2012 Read Article

Turquoise with Simulated Matrix

Rebecca Tsang , Jan 27, 2017 Read Article

Turquoise with Fingerprint Pattern

Tara Allen and Amy Cooper , Oct 17, 2013 Read Article

Turquoise from Western Arkansas

Jennifer-Lynn Archuleta and Nathan Renfro , May 11, 2018 Read Article

Recommended Reading

The Allure of Turquoise
Susan Arritt

Turquoise: Mines, Mineral, and Wearable Art
Mark P. Block

Turquoise Unearthed : An Illustrated Guide
Joe Dan Lowry and Joe P. Lowry

Featured Gems

Peridot

Found in lava, meteorites, and deep in the earth’s mantle, yellow-green peridot is the extreme gem.

Fancy Color Diamond

Dazzling brilliance. Captivating color. These are the planet’s most valued gems.

Diamond

Diamonds are among nature’s most precious and beautiful creations.

Emerald

Emerald is the bluish green to green variety of beryl, a mineral species that includes aquamarine.

Citrine

Citrine is the transparent, pale yellow to brownish orange variety of quartz.