Recognising Real Turquoise: Treatments, Imitations and Simple Tests
Natural, stabilised, reconstituted, dyed howlite or glass: what is on the market on the market, the signs that should raise doubts, and tests that are safe to carry out.
Key points
| Nature | hydrated copper aluminium phosphate, triclinic system |
|---|---|
| Hardness (Mohs) | 5 to 6 (a little under 6 in the finest qualities) |
| Density | about 2.6 to 2.9 |
| Common treatments | resin stabilisation, dyeing, reconstitution ("block") |
| Common imitations | dyed howlite or magnesite, glass, plastic, ceramic |
| Sources | Iran, Sinai, southwestern United States, China (Hubei) and others |
| Most useful test | magnifying glass: the colour and the matrix (veins) should look natural |
| If the piece is valuable | certificate from a gemmological laboratory |
What is really sold under the name “turquoise”
Turquoise is a hydrated copper aluminium phosphate with a hardness of 5 to 6 on the Mohs scale. It is porous, often soft and rarely of ideal quality. This is why the market offers five very different products under the same word.
- Untreated natural turquoise: hard, dense and beautifully coloured. It is rare and expensive, especially in large sizes.
- Stabilised turquoise: a soft or chalky turquoise impregnated under pressure with resin (or sometimes sodium silicate) to harden it and fix its colour. The material remains turquoise. The treatment is widespread and accepted, provided it is disclosed.
- Dyed turquoise: a pale turquoise artificially coloured. The colour may fade or bleed.
- Reconstituted turquoise ("block" in the trade): turquoise powder, sometimes very little of it, bound with resin and pigmented. Part of the commercial "block" is entirely artificial, with no turquoise at all.
- Imitations: dyed howlite or magnesite, glass, ceramic, plastic. Ancient Egyptian faience was already an imitation of turquoise.
The word "turquoise" on its own therefore does not tell you which of these five cases you are looking at. An honest description says "stabilised", "reconstituted" or "howlite dyed blue".
Warning signs
No single sign is enough on its own. It is the accumulation of signs that counts.
| Sign | Natural or stabilised turquoise | Imitation or reconstituted |
|---|---|---|
| Colour | Sky blue to blue-green, often slightly uneven, paler here and deeper there | Perfectly uniform blue, sometimes too bright ("swimming pool" blue) |
| Veins (matrix) | Brown, grey or black, irregular, following real fissures and varying from one bead to the next | Regular black spiderweb network that repeats from bead to bead, sometimes drawn on |
| Surface under the magnifier | Fine rock texture, tiny pores, irregular grains | Colour concentrated in cracks (dye), blue granules set in a binder (reconstitution), round bubbles (glass, plastic) |
| Weight and feel | Dense stone, cool to the touch | Lightweight plastic that feels warm and heats up quickly in the hand; very smooth, heavy glass |
| Price | High for a large piece of fine colour | Very low for a large bead or a "perfect" cabochon |
Howlite is naturally white and very porous (hardness 3.5), which makes it easy to dye. Its black-veined pattern is often the most convincing imitation: see our page turquoise or dyed howlite.
Simple, safe tests
These steps do not damage the piece. None requires acid, flame, blade or chemical product.
- Read the description: look for "natural", "stabilised", "reconstituted", "dyed" and "howlite". A reputable seller will answer your questions.
- Examine under a magnifying glass (10x) in good light: colour gathering in every crack indicates dye; small identical blue specks in a paste indicate reconstitution; round bubbles indicate glass or plastic.
- Compare several beads on the same necklace: natural turquoise varies a little from one bead to another. Beads that are all identical, with the same vein pattern, more likely come from the same mould or the same block.
- Weigh and feel: a plastic bead is clearly lighter than a stone of the same size, and it feels warm. This test is only indicative.
- Rub a damp white cotton pad (lukewarm water only) on an inconspicuous spot. If blue comes off onto the cotton, there is surface dye. The absence of colour proves nothing: well-fixed dye does not come off.
- Listen: two beads gently knocked together make a sharper "click" if they are stone or glass, and a duller sound if they are plastic.
As for a scratch test, it is better to refrain: turquoise is porous, and a scratch leaves a permanent mark. The concept of hardness is useful for understanding (see the Mohs scale), but less so as a test for your own stone.
What these tests do not prove
A stabilised turquoise passes all of the tests above: it is natural, even if resin has hardened it. Conversely, a well-made reconstituted block can look natural, and some glass or ceramic imitations are very convincing. Only a gemmological laboratory, using infrared spectrometry, reliably detects resin, dye or binder.
Nor is there an automatic link between "treated" and "poor quality". A stabilised turquoise is often more durable than a chalky natural turquoise, and it can be very beautiful. What matters is that the treatment is disclosed. For a valuable piece (large size, antique jewellery, collector's item), ask for a certificate from a recognised gemmological laboratory.
Names to know and names that cause confusion
Several names refer to products that are not natural turquoise:
- Viennese turquoise: aluminium phosphate coloured with copper, manufactured since the 19th century.
- Neolith: a mixture of copper phosphate and bayerite, an industrial product.
- Gilson turquoise: a product developed by Pierre Gilson in the 1970s. It is a laboratory imitation rather than a synthetic turquoise in the strict sense, because of its binder.
- "China turquoise" or "block": trade names that sometimes cover natural stabilised turquoise and sometimes a reconstituted product. Ask for details.
- "Sleeping Beauty turquoise" or "Tibetan turquoise": names of origin. They do not guarantee the absence of treatment. The Sleeping Beauty mine in Arizona ended its turquoise production in August 2012.
Natural blue can also turn greenish over time: turquoise absorbs skin oils and cosmetics. This is not a sign of a fake.
Before you buy
Always ask for the exact nature (natural, stabilised, reconstituted), the origin if it is known and, if possible, close-up photos. Our product pages state the nature of the stone and the known treatments, with the note that photos are for illustration: see our commitments.
Our guide on reading a label explains the vocabulary of treatments, and the page real or fake stone gives the overview. For care, remember that turquoise dislikes household cleaners, perfume, prolonged sweat and ultrasonic cleaners.
Frequently asked questions
How can I tell whether my turquoise is real?
Look at it under a magnifying glass: a uniform colour, regular veins that repeat, or blue in the cracks are warning signs. Read the description (stabilised, reconstituted, dyed?). For a valuable piece, only a gemmological laboratory can answer with certainty.
Is stabilised turquoise fake?
No. It is real turquoise, impregnated with resin to harden it. The treatment is common and accepted, but the seller must disclose it.
Is blue howlite a form of turquoise?
No. Howlite is a different mineral, white and very porous, with a hardness of 3.5. It is dyed blue to imitate turquoise. It is sold honestly when the description says "dyed howlite".
Why does my turquoise change colour?
Turquoise is porous: it absorbs skin oils, cosmetics and moisture. It can turn green over time. This change does not mean the stone is fake, but it does mean it needs protection.
Can turquoise be tested with a heated needle or an acid?
No. These tests damage the stone and are not reliable, because plastic and stabilising resin react in similar ways. Prefer the magnifying glass, a damp cotton pad and a laboratory certificate.
Also read
The meanings mentioned belong to tradition and symbolism. They are neither promises of results nor medical advice. Back to Recognising real stones.