Turquoise is a popular gemstone known for its striking blue-green color. However, some turquoise stones can appear more green than blue, which leads many to wonder – can real turquoise be green? The short answer is yes, turquoise can naturally occur in various shades of blue and green. In this article, we’ll explore how turquoise gets its color, what makes a turquoise stone real, and under what conditions turquoise can appear green.
Turquoise derives its characteristic color from copper and iron impurities present in the stone’s composition. The blue hues come from copper, while iron lends a greenish cast. The final color depends on the relative concentrations of these elements. More blue copper leads to a deeper blue turquoise, while higher iron content produces greener turquoise.
What Makes Turquoise Real?
For turquoise to be considered real or natural, it must form in the earth as a secondary mineral through a geologic process. Turquoise begins as water percolates through aluminum-rich rocks picking up color-lending copper and iron ions. When this mineral-rich water encounters zones of phosphate and limestone, turquoise crystallizes and hardens into veins and nodules.
True turquoise only comes from a handful of regions globally with the ideal geology to facilitate turquoise formation. Famous turquoise mining locales include the American Southwest, Iran, Egypt’s Sinai Peninsula, and China. Each region produces turquoise with distinctive natural characteristics based on local geological conditions.
Natural turquoise can be verified through testing. Gemologists use techniques like spectroscopy and X-ray diffraction to analyze the mineral composition and crystalline structure. These tests can distinguish real turquoise from imitations like dyed quartz or reconstructed howlite. Physical examination also reveals natural signatures like matrix markings and color variations that indicate authentic turquoise.
How Does Turquoise Become Green?
While blue is the most coveted turquoise hue, natural forces can produce green turquoise under certain circumstances:
– **Higher Iron Content:** As mentioned, iron ions in turquoise impart green tones. More iron-rich source rocks yield greener turquoise. Certain deposits, like American mines in Nevada, are known for green stones.
– **Oxidation:** When exposed to oxygen, copper in turquoise oxidizes from blue Cu2+ ions to green Cu+ ions. This can occur near the surface of turquoise veins as water seeps past. Mined turquoise left untreated will also develop greenish patches.
– **Dehydration:** Turquoise contains water in its mineral structure. When a stone loses some of this water, it turns greener. Slow dehydration happens over time in dry climates. Rapid dehydration can be caused by heating a stone during polishing.
– **Matrix:** The veining and dark markings running through turquoise are called matrix. A high concentration of black limonite matrix interspersed with turquoise can impart more green color.
– **Radiation:** Natural radiation from uranium-containing minerals like vanadinite can alter turquoise’s molecular structure, reducing blue copper ions and shifting the color toward green. This occurs near uranium deposits.
So in summary, yes, real untreated turquoise can naturally occur in green hues due to iron content, oxidation, dehydration, matrix concentration, and radiation exposure. Not all green turquoise is fakes – stones displaying characteristic vein patterns and mineral composition can verify their authenticity.
Evaluating Green Turquoise
When examining a green turquoise specimen, consider these factors to help discern if it’s real:
– **Source:** Green turquoise is more common from certain geographical regions and mining sites. Natural Nevada turquoise often leans greener. If the stone came from a trusted American Southwest mine, it’s more likely genuine.
– **Color range:** Natural turquoise exhibits some color variation from mottled blue-green to yellowish matrix. Uniform “too perfect” green turquoise is questionable. Real stones have distinct, unique color patterns.
– **Matrix:** Examine veins and markings. Natural black or brown limonite matrix indicates authentic turquoise rather than dyed quartz.
– **Luster:** Natural turquoise is waxy with a slightly grainy surface texture. Fake stones often appear plastic-like.
– **Weight:** Natural turquoise is dense compared to fake stones. Judge heft relative to size.
– **Testing:** Advanced spectroscopic and X-ray tests by a gemologist can verify a stone’s authentic mineral components.
Green Turquoise Value
In the turquoise trade, deeper sky blue stones command the highest prices, especially the rare “robins egg” blue of Persian turquoise. Green turquoise is more affordable but still desirable in its own right. Some collectors even seek out rare natural green turquoise.
Greener turquoise can blend beautifully with settings in yellow gold or exhibit striking color patterns. Green Nevada turquoise with dark brown limonite matrix is a popular jewelry choice. Many Native American and Southwestern jewelers incorporate natural green turquoise into their designs.
While not as commercially valuable as blue, natural green turquoise maintains decent worth for a semiprecious gemstone. Quality stones still sell for $50 – $100 per carat. Exceptional specimens with preferred matrix patterns or rare green shades can fetch higher prices from collectors.
Enhancing Green Turquoise
The turquoise market prefers blue tones, so some green turquoise undergoes enhancement to improve color. Treatments like waxing, dyeing, and irradiation can make stones more uniform blue-green. However, most enhancement lowers value compared to untreated natural green turquoise.
Buyers should be aware of possible turquoise treatments:
– **Waxing:** Penetrating wax is used to deepen color and add luster. Waxing is the most common and acceptable enhancement.
– **Dyeing:** Teal dye is soaked into porous turquoise to change it blue. This alters the natural color significantly.
– **Irradiation:** Exposure to radiation turns greener stones more blue. Like dyeing, this creates an artificial appearance.
– **Reconstitution:** Crushed turquoise mixed with epoxy resin can be shaped into stones with unnaturally vivid color.
– **Synthetics:** Manufactured fakes mimic turquoise’s look but lack natural markings.
Enhanced turquoise should be disclosed at sale. Keep possible treatments in mind when purchasing, especially with bright blue-greens. Natural green turquoise has its own unique beauty derived from the earth’s processes.
Caring for Green Turquoise
To maintain the natural color and integrity of green turquoise:
– Avoid prolonged sun exposure which can dry out the stone.
– Store pieces in soft cloth bags to prevent scratches.
– Keep away from harsh chemicals like bleach which may alter color.
– Remove turquoise jewelry before activities like swimming, gardening, cleaning.
– When storing long term, wrap in acid-free tissue and avoid dramatic temperature changes.
– Have epoxy-resin treated stones re-hardened by a jeweler every few years.
With periodic cleaning and care, high quality natural green turquoise will retain its original beauty for many years. The range of blue to green only enhances turquoise’s aesthetic appeal.
Conclusion
While typically associated with pure blue hues, natural forces can produce authentic turquoise stones with green coloration. Higher iron content, oxidation, dehydration, matrix patterns, and radiation exposure all contribute to turquoise’s occasional green shades. Nevada and American Southwest mines are prime sources for untreated green turquoise. When shopping for turquoise, quality markers like vein matrix, surface texture, density, and professional testing can verify a green stone’s natural properties. Although not as commercially popular as blue, natural green turquoise has its own distinctive beauty and collectors who appreciate its natural diversity. With care and enjoyment, green turquoise can make a cherished addition to jewelry and mineral collections.
