Image taken by S.W. Aber, 2/2010.

GO 340 Gemstones & Gemology
ES 567 Gemstones of the World
Dr. Susan Ward Aber, Geologist & Gemologist
Emporia State University
Emporia, Kansas USA


The crown shown above is the famous diadem wedding present from Emperor Napoleon I to Empress Marie Louise his second wife. Enlarge the image by clicking on it. Originally, it was fitted with 79 emeralds and the current 1000 diamonds that total 700 carats. The Persian turquoise set in both silver and gold metal was altered in 1952 by Van Cleef and Arpels, a legendary Parisian jewelery store founded in 1896 by Charles Arpels and Alfred Van Cleef ( These jewelers obtained the crown from Hapsburg relatives of Empress Marie Lousie and sold the turquoise crown to Marjorie Merriweather Post who gave it to the Smithsonian Institution in 1971. This lovely piece was on display at the 2010 Tucson Gem and Mineral Shows where it was photographed by the author as a wonderful example of recycled jewelry of note and turquoise in particular!

Turquoise is hydrous copper aluminum phosphate, CuAl6[(OH)2/PO4]4 4H2O (Schumann, 1997, p. 170). It varies in color from a sky blue to blue-green or apple-green, and is frequently fashioned with the matrix rock and interspersed vein rock. The veined material is called "spiderweb" turquoise. The blue color changes to green with high heat (of soldering) and exposure to light, perspiration, oils, cosmetics, household detergents (always remove turquoise rings before washing hands or dishes). It has a hardness of 5-6, cleavage, and a conchoidal fracture. The specific gravity is 2.31-2.84 and it is in the triclinic crystal system, crystals are rare. It has a waxy luster and both the fluorescence and pleochroism is weak.

Turquoise is opaque and has one of the highest values among opaque gemstones, second to highest quality jade and lapis (The Image). It is a treasured gemstone, used for beads by Egyptians as early as 5500 B.C., and inlaid in gold by Sumerians and Egyptians for jewelry such as necklaces, bracelets, earrings, and headdresses. It has been popular in the Orient and with South and North American Indians. For more history and lore, visit CW Jewelers and Turquoise Blue Sky...Blue Stone by Bob Jones, Senior Editor of Rock and Gem magazine reproduced at

Many people appreciate the lustrous, waxy luster of this gem and enjoy working with it as well. Lapidary Journal ran a step-by-step article on cutting and fashioning a freeform cabochon of turquoise. The Turquoise Mystic by Tom and Kay Benham can be viewed at and

Images taken by S.W. Aber, 2/2010.

Image taken the Smithsonian Natural History Museum, Washington, DC.
Photo by S.W. Aber 4/2009.
The oldest turquoise source is in Sinai, Egypt, where the mines were worked for thousands of years and believed to be worked out by 4000 B.C. although it some was rediscovered in the mid-nineteenth century and worked on and off until the 1900s. Mines in Iran were known for good quality nodules and vein material in the sky blue color. Turquoise is also found in Afghanistan, Argentina, Australia, Brazil, China, Israel, Mexico, and the US, primarily New Mexico, Nevada, Arizona (but also Texas, Colorado, and California). It has been used extensively in tribal jewelry in central Asia.

<<< Image left is turquoise from Arizona (Zuni bracelet), Lynch Station, Virgina, and Los Cerillos, New Mexico.

The pure blue color is rare and often turquoise is intergrown with malachite or chrysocolla, along with the host rock matrix. In the US, the aluminum (Al) in turquoise is partially replaced by iron (Fe) and thus, strictly speaking, the mineral chalcosiderite, not turquoise (Schumann, 1997, p. 170). Turquoise is a secondary mineral formed in the alteration zone of hydrothermal replacement deposits, often associated with copper deposits in arid, desert environments.

Image taken from
The Image.

Image taken from
Jewelry Central.

Image taken from
Jewelry Central.

Image taken from
The Image.

Image taken from
The Image.
Turquoise is porous and therefore treated by soaking in a vat of artificial resin or plastic-polymer, which also hardens and stabilizes the surface. The color is enhanced with oils, or paraffin, aniline colors, copper salts, etc. Turquoise is reconstituted when the mineral is crushed into a powder, soaked or baked with a adhesive mixture; finally, this solid material is pressed and sold in blocks that are easier to cut and fashion than stabilized material. All of these enhancements reduce the value of the gem and should be disclosed at the time of a sale. Additionally, synthetic turquoise has been on the market since 1970, and imitations of turquoise have been around for thousands of years. Early imitations were made from glass and porcelain, while later imitations are various plastics or dyed howlite. Read about various treatments at, Turquoise Rough, A ColorWright Web Store, and follow their internal links showing images of specimens treated and natural.

Turquoise is December's birthstone and reserved for the 11th year anniversary. It is set in both gold and silver, often with red and pink coral, as well as mother of pearl, malachite, lapis, and sugilite. The Native American Jewelry or "Indian style" silver jewelry is relatively new, that is unknown prior to 1880 (Jewelry Central). A trader persuaded an Indian artist to make the turquoise and coin silver jewelry, in addition to the more traditional solid turquoise beads, carvings, and inlaid mosaics.

Photo date 3/02,
© S.W. Aber.

Dyed howlite.
Photo date 10/99,
© S.W. Aber.

Learn more about turquoise by visiting:

References to View and Read

  • Schumann, W. (1997). Gemstones of the world. NY: Sterling Publishing.
  • Return to the Syllabus or choose another gemstone below.

    Alexan drite Amber Amethyst Chalcedony Diamond Emerald
    Garnet Jade Malachite Opal Pearl Peridot
    Ruby Sapphire Tanzanite Topaz Tourmaline Turquoise

    This page originates from the Earth Science department for the use and benefit of students enrolled at Emporia State University. For more information contact the course instructor, S. W. Aber, e-mail: Thanks for visiting! Webpage created: November 15, 2000; last update: December 4, 2012.

    Copyright 1999-2012 Susan Ward Aber. All rights reserved.