Can someone please help me to identify an inclusion inside a stone which appears like a fingerprint on the right side of the stone? Thanks!

Thank you so much for your fast response!

How much does it matter in what respect?

It depends on where the extra facet is located, and how large it is. The macro photo you posted is excellent quality, but does not give an idea as to scale. Given the position on the crown, it is probably minor in terms of any impact on cut quality, and clarity should not be impacted at all (in fact, often extra facets are cut because the cutter wants to eliminate an inclusion). The visual appearance may however suffer a little, since it is in a visible position and the stone may seem slightly asymmetrical to a careful observer. I assume it's a round sapphire BTW, given the pictures.

However, I think you should get the stone graded professionally - either by GIA (if your purpose is to have something that commercially helps you sell/value the stone) or by a competent appraiser (if you want to know all the ins-and-outs of your gem to satisfy your curiosity), rather than relying on advice that however well intentioned is based on two incomplete photographs and no understanding of your objectives and situation (are you buying? selling? exchanging? inheriting?)

Figuring out whether it's a diamond or a sapphire is relatively easy - any jeweller worth its name should be able to tell you.

Looking at the first photo, I cannot see any double refraction of  the edges, but the stone may have been cut along its optic axis precisely to make ID from a photo difficult. The facet edges could be either a not-very-carefully-cut diamond or a sapphire. At any rate a thermal conductivity test should easily distinguish between sapphire and diamond, and a refractometer will provide confirmation.

Natural vs. irradiated colour is tougher without proper instruments - but if it is a diamond I'd rule natural colour out in that tint. A diamond with that natural colour would be worth tens of thousands per carat as a small stone, and hundreds of thousands as a stone of 1 carat + (look at this one for comparison - and it ain't expensive: http://rockdiamond.c...n-old-mine-cut-r3512 ) - and it would always be accompanied by a GIA OR Gübelin report stating colour origin at the very least... which I assume your stone doesn't have.

What are you going to do with it, if I may ask? Regardless of what it is, it seems a pretty stone.

Oh by all means have it tested. Any diamond tester can tell you. at 13mm it must be a large size so give us more detail. where did you buy it an when... and if you don't mind... how much did you pay?

Sounds like a sapphire for sure.....

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It does not appear that the hot-pink fluorescence happens because of “the violet visible component UV mixed with white.”  I believe it could be a synthetic stone that glows hot pink over the parcel of the stone.

It does look like red - I stand corrected. Which usually implies there is chromium, if it is a corundum. Yet the colour seems pure blue, if anything with a grey mask, but no purple or violet, which is what I would expect with chromium in the stone. Interesting. CZ - which is the other possibility I was considering - usually glows yellowish. At this point I'm intrigued, and would really like to know what it is.

ETA - unless... unless... do you know if the UV lamp you are using is Short or Long Wave? If it is (as I am now suspecting) LW, then the reddish glow is typical of some flux-grown corundum varieties. Then treat the stone with titanium diffusion, and voilà a nice pure blue comes out. Or it could be a synthetic spinel, which also fluoresces red under LW.

How do you clarify the pinpoints (cloud) and the extra facet since simulants are less likely to have these? It could be a natural sapphire. Anyway, I’ll keep it in my collection box. Thank you for this fantastic environment!

I hope you don’t mind me adding more pictures of the stone being held under UV black light. These images represent the stone in a distance away from the black light and facing way from the lamp. Is this a characteristic of synthetic stone? Yet, I’m in agreement with you that the price and the size do create a problem for the stone to be natural.

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