How to tell if garnet is real

[Picabia]

Hi again,
I recently purchased some sub-par demantoid garnets from ebay to start a little collection. They''re from Thailand, and although the sellers have terrific feedback, their super low cost has me wondering. When they arrive, how can I figure out if they''re real? Is there a simple test to determine if a stone is garnet vs glass? What about determining if they''re actually demantoid? Obvious for serious purchases I''d only trust a reputable dealer, but I wanted to buy some cheap stones to figure out what I like, what things look like in person, etc. However I do want them to be real!

 

[T L]

I don''t know the simple tests you can perform, but sometimes sphene is sold as the more expensive demantoid, and sphene is doubly refractive, which means you can see the facets double when light reflects out of the stone. However, YAG, a synthetic garnet is also sold as demantoid too, and I think you need an RI test, in particular if the demantoid has no visible inclusions.

 

[RockHugger]

Bad thing with demantoids is the refractive index is higher then most refractometers will read. It''s mostly trusting your vendor unless you have the whole gemmo lab.

 

[Picabia]

Wow--that''s a lot of refraction.
Is there any way to simply tell if a stone is a garnet? Even if not demantoid?

 

[Michael_E]

No, there is no simple way to tell if any stone is natural without either seeing the rough or at least having a variety of tools. Glass can mimic almost anything and can have added elements that will raise it''s R.I. to well over 2, (which is higher than any garnet). You can generally pick up some clues just by viewing you stones with a good loupe. Cheaper natural stones almost always have some inclusions, whereas synthetics and glass don''t have any, (or they will be obviously different than those in natural stones). As the price of the stones goes up, so does the benefit in faking more natural looking features in synthetics, so always have more expensive stones checked by a competent geologist or lab.