Back to IGS | FAQ | Contact

Diffused Natural Sapphire Versus Synthetic Corundum?

I recently had a customer think they had a synthetic Sapphire when I believe its a beryllium diffused natural sapphire. The GIA person that tested it couldn’t say what the material is. Does anyone out there have a similar experience where a jeweler store GIA person can’t ID a material to rule our Diffusion of a natural sapphire as part of a ID Test? Im very curious because I always thought an emersion Cell test wit the proper RI Solution showed diffusion. Any feedback would be greatly appreciated. Thank you!

Did you see any inclusions in it? Growthlines? Can you describe it more?

PS. An GIA exam doesent make you an expert. Only experience will do that. I am “only” a IGS certified gemologist and i can tell you that i have beaten both GIA and FGA people in identfication contests.:wink:
Many gemologists ends up working with mostly Diamonds and by so they dont get the practical experience with coloured gemstones.

1 Like

I sold a diffusion treated sapphire ring to a client (disclosing the treatment) and they took it to a Jeweler who told them it was a synthetic Sapphire. I rang the Jeweler myself and told him that it was diffusion treated and he said that my client didn’t tell him that…my client shouldn’t really have to should they?

Yes I totally Agree. I have had different GIA People give different results on the same stone!
But the tough thing is the customer will only believe when they hear what they want to hear it seems no matter the Data! I mean this one GIA Grad. is like a GOD to this Client but has only 17 years of Diamond experience to say my 45 years of gem cutting colored stones and IGS Credentials and two other GIA People with different outcomes.

1 Like

It’s still natural Sapphire but Treated.

1 Like

The other thing is it seems nearly 90% of Sapphires and rubies seem to be heated these days leaving very few truly natural Sapphires out there. When the best color is found in a unheated, untreated sapphire very few people can afford the price. On the other hand when a heated sapphire or worse yet diffused sapphire is picked out because of it’s even color and tone , Once the customer hears it’s treated the mind set is like " oh it’s not real!" Welcome to the world of Corundum!

1 Like

I think what bothered me the most was that this GIA person never tested the stone but only visually inspected it and said it was too clean to be a natural sapphire. Then he proceeded to down IGS credentials like he was on some sort of Throne of Knowledge.

1 Like

If you feel that high-tech analysis of the piece (non-destructive) would be worth your time an $ I have a person at our new Maine Mineral and Gem Museum that has all the tools needed. He does analysis for me when I find a piece of rough that I can’t identify. He also does detailed work for the hard-rock miners in New England.
Here are the links:

But let me now first so I can make an introduction to lubricate the contact. (I am on the board of trustees)


Hi Thanks. After testing it was determined to be a synthetic. However thank you for the information. - Mike

Just for interest sake commercially mined sapphires have been professionally heat treated for some 50 years

Yes I know but Diffusion is different than Heating to obtain a desired color. Agree?

1 Like

depending on the heat I understand that Beryllium treated sapphire is heated nearly to melting point this causes the atomic structure to change with some eons causing vacancies which are then filled by the Beryllium thus changing the atomic structure of the gemstone that is pretty basic and I am sure some of our other community friends may have more of an understanding than me

But is beryllium diffused more of an external coating. I know when it’s observed in an emersion cell the outer edge tends to be more pronounced , almost halo looking. Any thoughts?

Hi Mike,
I read through your posts and wanted to let you know that if you went to this jeweler and he gave you a identification call on a gem by only looking at it, leave and never return. While this individual likely took a course or two at GIA, likely diamonds and diamond grading, he is very likely not a GIA Graduate Gemologist and if so a piss poor one. I seriously doubt he would have passed to final exam which requires a passing score of 100% and not a point less.
I have had numerous customers that have had Jewelers tell them things about gems that were simply not true and even appraisers, but, customers will believe a person standing in front of them more so than someone who is not there and most folks give undo credibility to jewelers not understanding that a jeweler is not necessarily a gemologist and a gemologist is not necessarily a jeweler.
A diffusion treated stone is typically pretty simple to ID by turning the stone table down on a diffusion plate under 30x or so and one can see color concentrations at the facet junctions. Synthetic corundum also requires primarily magnification but also requires a good deal of knowledge of what to look for and the absence or prescience of inclusions and what type of inclusion to look for. Since the optical characteristics of natural and synthetic corundum are virtually identical magnification is going to be your key test to distinguish one from the other.