It looks synthetic to me. The rays of the star are very thin and sharp. The bottem of the stone looks perfectly flat to me. That is a hallmark of synthetic star stones.

Many people believe that synthetic stones are perfect. That's why these stones are treated to create imperfections to simulate natural stones.

The fact that you bought in Vietnam near the source makes it extra suspicious.

So based on the pictures i would say, Synthetic.



Peter

Hi Kit,


To me it looks like a natural stone that has been treated, this is common. For enhancing the "star", known as asterism, the most likely treatment is diffusion:

Diffusion: The use of chemicals in conjunction with high temperatures to product color and/or asterism-producing inclusions.


taken from the enhancement code list from Alpine Gems (could not find a definition on gemdat or mindat).


http://alpinegems.ca/catalogue.html


regards,

stephanie :-)

I have a similar red-colored star corundum, my is not synthetic, it was probably enhanced, the imperfections are evident under magnification.

Thanks everyone...still confused...so I took some of the back with sunlight on it. Seems a little uneven, see what you think now...maybe this will tell?

Kit,

The stone has been cut and polished. Accordingly, 'the flat back of it' gives no information on its origins. I agree with Stephanie and others that your piece has geological origins. As to whether or not it has been treated for enhancement, I'm not prepared to guess off the photos.


Whatever, it's nice! Enjoy :-)

When I look at the stone on the polished/star side with a lens I can see a pattern of concentric formations - the stone was produced by cutting across the corundum crystal, perpendicular to its c-axis.

Sofia

ATS,

Are you talking about your own stone of the pics that Kit put up here? If the latter, I can see no 'concentric rings' in Kit's pics (nor, given the low level of definition and the lighting, would I expect to be able to do so).


Where present, I'd say that curved growth lines in corundum were diagnostic for corundum produced by the flame fusion process. In geologically produced corundum - and also in flux grown and some other synthetic production, one would expect to see straight growth lines intersecting at the expected 120 deg angle.

OK...thanks everyone...& promise these will be the last pictures! lol I took them at night with flashlight, some pretty odd, you can see some of the dark specks & the bright spots that are in the stone...plus something new I've not noticed because the stone is naturally darkish...there seems to be an "extra" star thing on the side and sort of two different colors in the stone. Since it's by "flashlight" the color of the stone has a more bluish color than purple. Maybe, at least, this will help in future ID of other stars as to their being "natural" or man made..?

I meant my stone, straight lines. I cannot see what's on Kit's too well...

Sofia