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Taaffeite vs. Spinel

I read recently that older parcels of Spinel were sometimes mislabeled and contained Taaffeite. I couldn’t find much on this site regarding Taaffeite; what characteristics differentiate it from Spinel? Thanks all

I would not know the differences but I did find this on wiki https://en.wikipedia.org/wiki/Taaffeite

Thank you, yes I had done some digging and saw this. A friend is a GIA appraiser and I purchased quite a few spinel in the late 90’s now their color looks odd to me. Hopeful? Dreamer, maybe :slight_smile: But she hasn’t seen any Taaffeite but should know more than me. Has anyone actually seen it? Thx much for your response.

Hi, Taaffeite has a very similar chemical make up to Spinel, one very simple way to find out if you may have a Taaffeite is that it is doubly refractive where as Spinel is singlely refractive
when undertaking my gemmology Diploma I was testing some spinels and believe it or not, I actually found a Taaffetie in amongst some rough spinel
to ensure that I had a Taaffeite I had it tested by Laser Ablation with positive results
see photo of Taaffeite 3.15 cts that I faceted

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Thank you, that’s the info I needed. What a treasure you found! I love the kite shaped cut, stunning. Thx so much for sharing your knowledge and this image.

@SydP Nice job on the faceting…

Taafeite crystals are Hexagonal while Spinel is Octahedral.
Spinel hardness is 7.5-8 while Taafeite is 8-8.5
Spinel is generaly ftee of inclusions while Taafeite is not!
There are other tests with SW and LW also Taafeite is doubly refractive

This topic has me wondering, how often do faceters by stones as spinel that end up being something else?

I ask because one of the IGS articles on recutting sapphires shows an example where someone bought a relatively inexpensive spinel and during recutting realized it was actually a very expensive Sapphire!

That’s a good question, when I was studying my gemmology diploma, I was using the spectroscope to study rough garnets I had, which I purchased from a good source some 35 years ago from East Africa.
While I was testing I discovered a different type of spectrum to the normal Almadine and Rhodolite garnets. this turned out to be a Ruby which I have since cut 1.2 cts clean, and set in a pendant.
I had been selling these rough garnets at gem shows for several years before I found the ruby and often wonder if someone was lucky enough to buy a ruby from me as garnet rough at around 3$ per cart…
Yep it can happen and does happen.:slightly_smiling_face: