I am new to this but I need to be able to identify genuine black spinel as opposed to black onyx. I realise spinel is harder but is there a way to tell them apart easily? Is there some simple test equipment I could buy?
I should mention that I am trying to make the identification of stones that are already set in silver jewellery. I live in THailand which apparently is one of the few sources of black spinel having a mine in Kanchanaburi but even local traders there refer to black spinel as being black onyx - hence my confusion.
The faceted black spinel which I saw a lot of in Thailand and which was all referred to as "black onyx," had a noticeable higher luster and sharper faceted edges - they both are listed as having vitreous luster in texts, but side by side, I see a luster difference. If you buy some specimen stones for comparison I think you will see the difference - especially with a loupe and a good light.... look at the fracture surfaces (spinel is chonchoidal and vitreous) and see if light behind the stone shows any banding near the thin edges. A refractometer reading would be your best proof, though not always possible of course - the black spinel will have a higher RI than other spinel - 1.740 up to 1.777, much higher than chalcedony (black onyx).
Users browsing this forum: No registered users and 1 guest
You cannot post new topics in this forum You cannot reply to topics in this forum You cannot edit your posts in this forum You cannot delete your posts in this forum You cannot post attachments in this forum