Identifying and testing fake Turquoise
Turquoise is actually quite a rare gemstone – but there are many fake Turquoise pieces for sale across the internet.
It can be extremely difficult to identify these fake pieces from images, even for experienced collectors.
Having the piece in your hands is by far the best way to tell, however, I’m now going to run you through a few simple ways to identify whether a piece is fake or not.
First of all – there are several things that may be done to Turquoise, which are purely treatments for the stone to be more usable in jewellery or lapidary.
Genuine natural Turquoise may be sold:
As it was mined – these pieces tend not to be used for jewellery or polished, as they are quite brittle.
Stabilised – these pieces are genuine Turquoise which have been treated to make them more suitable for polishing. They may be soaked or coated in wax or epoxy. It simply makes the stone less likely to break during any lapidary work.
Dyed and Treated – some Turquoise is dyed to give it a better or a more even colour. As long as this treatment is actually mentioned, it seems fair to call it ‘genuine’, although selling a dyed piece without disclosing the dye treatment is unfair to the end customer at best.
Common types of fake Turquoise include:
Turqurenite – a fake form of Turquoise usually composed of dyed Howlite, or dyed Magnesite.
Block / Reconstituted Turquoise – small pieces of genuine Turquoise ground up and added to a matrix with resin or other minerals, to form a blue block. It contains hardly any Turquoise – if any.
Plastic / Epoxy / Resin – simply, a plastic imitation stone. This should be reasonably easy to identify, although some sellers have added metal or other items to give the piece some weight.
Other stones – other stones that look like Turquoise – including a stone from Africa sold as ‘African Turquoise Jasper’.
The various tumblestones and beads to the right are all ‘fake’. You can imagine how it would be possible to pick a fake over a real one!
How do I tell?
Certain fake pieces can be identified quite easily by sight or weight – some can not.
One simple test involves heating a pin and placing it on the surface of the stone – a burning plastic smell will indicate that the piece has been treated, or is an imitation.
Another test involves soaking the piece in a strong solvent, such as Acetone overnight. It is possible that some dye will leach out into the solvent, giving you a solid indicator that the piece is either fake or dyed.
A good test is to check out the lines on the Turquoise – on genuine Turquoise and on dyed Howlite, these lines will be sunk into the stone itself. On some fake pieces, they are painted or dyed on and cannot be felt with a fingernail.
Destructive testing techniques.
One simple test that can be done on loose pieces of Turquoise that you own is… well, break it.
In these photographs, you can see two specimens. One is synthetic Turquoise, sold as Turqurenite. One is genuine Turquoise, which I broke for this article.
The synthetic Turqurenite nugget has a large white void in the middle – which shows us that it has been dyed, and that the dye has not penetrated all the way through. This piece is likely Magnesite, from the size.
The genuine piece has colour all the way through. This won’t always be the case. A constant, steady blue colour can be a sign of fake Turquoise – although some can be genuine.
Most genuine Turquoise specimens will have various shades of blue, white, and even green.
Mohs hardness testing.
One of the most effective tests you can do with specimens is to check the hardness of them.
The most common substitutes for genuine Turquoise are Howlite and Magnesite.
On the Mohs hardness scale, the hardness of Howlite is 3.5, and the hardness of Magnesite is 3.5-4.5. Genuine Turquoise is 5-6.
This means we can use minerals of other hardnesses to test the specimens, as shown in the photographs.
We have written a separate article for information on how to perform a Mohs hardness test.
To sum up – there is unfortunately a hell of a lot of fake Turquoise being sold. This is especially true in cheap ‘silver’ jewellery, which often turns out to be silver plated brass from India – illegally stamped and illegally sold.
Turquoise mounted in jewellery is very hard to test without destroying – so unfortunately tests in the shop, or at the market stall are almost non existent. Experience is all you have.
These tests will sometimes help identify – however, ideally, they should be combined with other gemological tests such as a refractometer. Reputable sellers will be able to provide evidence of their source, or have the knowledge to test the specimens.