Turquoise is a popular gemstone that has been used in jewelry and ornamental objects for thousands of years. Valued for its striking blue-green color, turquoise was considered a holy stone by many ancient cultures. But with its rise in popularity, fake and treated turquoises have flooded the market, making it difficult to discern real, high quality turquoise. Learning what to look for can help you identify genuine turquoise and avoid being fooled by imitations.
Look at the color
The distinct color of turquoise comes from its composition – it’s a hydrous phosphate containing copper and aluminum. The best way to test if turquoise is real is to examine its color. High quality turquoise has an evenly distributed, intense robin’s egg blue or blue-green hue. The color should not be too light or dull.
Fake turquoises are often dyed howlite or reconstituted stones made from crushed turquoise chips. These imitations tend to have an unnaturally bright blue-green color that looks artificial. The dyed color may also be concentrated in certain areas rather than evenly distributed throughout the stone.
Natural turquoise can also be treated with wax, plastic or water to improve the color. This gives the stone an overly vivid or waxy appearance. Untreated, high grade turquoise will have a more muted, natural looking color.
Check for matrix
Most turquoise contains a web-like matrix pattern of darker veins running through it. This matrix is made of the host rock in which the turquoise formed. The presence of matrix indicates the stone is natural rather than fake.
Fake turquoises will lack any natural matrix. The matrix may also appear too uniform or artificial looking. Low quality real turquoise is sometimes impregnated with plastic to alter the appearance of the matrix. Examine the matrix closely to make sure it looks natural and matches the features of the stone.
Look for variations
Natural stones, including turquoise, will have some variations in their color and matrix patterns. Each stone is unique. Fakes and low quality stones will look overly uniform and consistent.
Examine the turquoise closely under proper lighting to check for natural variations. There should be some differences in shade and matrix throughout the stone. Regular color or lack of matrix indicates the turquoise is likely man-made or treated. Natural turquoise also may have some small dark spots or speckles along with the variations in color.
Check the quality of polish and cuts
Turquoise is relatively soft, rating 5-6 on the Mohs hardness scale. It’s prone to scratching and pitting. Examine the polish and any carved details of a turquoise specimen. Fakes may have a glassy, perfect polish with sharp detail work.
Natural turquoise will lack high polish and show some faint surface scratches or shallow pits. The polish may appear subdued rather than highly reflective. Any intricate carving or cuts will seem rounded rather than perfectly sharp. Signs of wear indicate a natural stone.
Consider the price
Because it’s rare in quality form, turquoise is one of the costlier gemstones. While price isn’t always a guarantee, inexpensive turquoise is more likely to be fake.
Real, untreated turquoise over 5 carats will cost over $1000 per carat. Exceptional stones can reach up to $10,000 per carat. If you find a large, high quality turquoise selling for a bargain price, it’s wise to be skeptical. The turquoise may be fake or treated to enhance its appearance.
Ask about origin
Most natural turquoise on the market comes from just a few sources. The primary source countries are the United States, Iran, Afghanistan and Egypt. The American Southwest and Iran produce turquoise considered the highest quality. If the seller can’t confirm the turquoise originated from one of these known sources, it may be fake.
Turquoise is also commonly treated and even reconstituted using turquoise dust and chips from these same sources. Be wary of vague claims of “American turquoise.” The turquoise may be altered rather than natural even if the source country is accurate.
Examine under magnification
Under close examination, true turquoise will reveal veins of matrix and pyrite running through it. Use a 10x jeweler’s loupe to look for small surface abnormalities, tiny natural pits, spiderweb matrix and flattened crystal growth. The stone may also have small dark circles visible under magnification.
Fake turquoise made of plastic or reconstituted stone will appear too perfect and flawless. There will be no identifiable crystal structure. No small natural details will be visible under magnification. The turquoise may also look artificial and overly uniform.
Test hardness
Since turquoise ranks at 5-6 on the Mohs hardness scale, you can test by trying to scratch the surface with a steel knife or nail. The blade should be able to scrape turquoise quite easily. Fakes made of plastic or glass will withstand scratching.
You can also try scratching the turquoise against a piece of quartz. Real turquoise will be easily scratched by the 7 ranking quartz while fakes will remain unmarked.
Perform a heat test
Heat can help identify fakes and treated stones. Natural turquoise contains hydrated copper which causes it to crack or turn grayish under high heat. A simple heat test involves placing the turquoise in a stove or kiln heated to about 200-250°C for two minutes.
After cooling, examine the stone. Untreated turquoise will become paler or develop surface cracks. Plastic and glass fakes will be unaltered. Stabilized stones may withstand minor heat exposure but turn chalky at higher temperatures.
Check for fluorescence
Under ultraviolet or black light, turquoise typically exhibits a yellowish fluorescence. Natural blue turquoise will turn greenish. Enhanced and treated stones may show no reaction under UV light at all.
While a lack of fluorescence doesn’t always mean the turquoise is fake, it can help spot treated stones. The strongest reaction indicates untreated, natural turquoise. Weaker or no fluorescence is a sign of stabilization or other enhancement.
Specific Gravity Test
Measuring specific gravity can authenticate turquoise. Real turquoise will sink in heavy liquids with a SG of 2.60 to 2.85.
To test:
- Obtain heavy liquids like jewelry grade zinc iodide, diiodomethane or methylene iodide which have a range of specific gravities from 2.6 to 3.3.
- Place a small, clean sample of the turquoise in the various heavy liquids one by one, starting with the lowest specific gravity.
- If the turquoise begins sinking in any liquid, note the specific gravity. The turquoise is likely real if it sinks in liquids with a rating between 2.60 – 2.85.
Fake turquoise made of plastic, glass or resin will float in these heavy liquids. Treated stones may sink but below the 2.60 – 2.85 range.
| Turquoise Type | Expected Specific Gravity |
|---|---|
| Natural | 2.60 – 2.85 |
| Stabilized | 2.50 – 2.80 |
| Fake plastic | Below 2.50 |
Conclusion
It takes careful examination to confirm genuine turquoise. Natural stones have distinct markings, like matrix and pyrite, visible under magnification. Quality turquoise will show variations in color but no artificial treatments. Authentic turquoise also reacts to heat and UV light. While testing can help weed out fakes, it’s also important to buy from reputable, high-end jewelers to ensure you’re getting real turquoise.
