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 Post subject: This stone is not synthetic sapphire -- what is it?
PostPosted: Fri Feb 18, 2011 1:49 pm 
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Location: Santa Barbara
I bought a stone on eBay a while ago from a place in Thailand that was sold to me as synthetic sapphire. I was dubious even when it arrived because it was kind of the wrong color (more a turquoise greenish-blue with green flashes than the blue-purple you normally see in synthetic sapphire) and seemed more dispersive than my usual experience with sapphire -- but I didn't really think about it too hard.

This morning I tried scratching it with a cheap blue topaz I have and it scratched easily. I was unable to scratch another synthetic sapphire and a cz with the same blue topaz.

So what is the stone I have, then? The scratch test indicates it's too soft to be sapphire or cubic zirconia. I guess it could be synthetic spinel? (Which the blue topaz does seem to scratch, though it's slightly hard for me to tell because the synth spinel I have was pretty scratched up already.) Though the green flashes I see in it seem to counterindicate synthetic spinel (at least, all the synthetic spinel I have seen has purple flashes instead of green flashes).

Could it be a deep london blue topaz? The shade of blue is about right for this, but I assume the green flashes (and higher dispersion... although I don't feel comfortable about my ability to judge dispersion so take that with a grain of salt) rule that out too. I'm hoping this is not it, in any case, because then I start worrying about radiation treatment from random place in Thailand un-vetted by US regulation... or am I just being paranoid?

Is there an easy test I can do (I don't have any equipment really) to figure out?

Thanks!


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 Post subject: Re: This stone is not synthetic sapphire -- what is it?
PostPosted: Fri Feb 18, 2011 1:57 pm 
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Let me see if I can add a pic. This is from the vendor but is pretty accurate:

Image


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 Post subject: Re: This stone is not synthetic sapphire -- what is it?
PostPosted: Fri Feb 18, 2011 2:29 pm 
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Yikes.
Where to start.

#-o Using gems to scratch other gems is never a good idea. Actually it's a really BAD idea.

A gem can not be ID'd from a photo. A gem can NOT be ID'd using a series of dangerous scratch tests.
:!: You can actually shatter diamonds attempting scratch tests.

A gemologist can sort this confusion out for you in 10 minutes or less, by testing with optical instruments.

You live in Santa Barbara; there are several qualified folks there who can help you.

Let us know what you discover.


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 Post subject: Re: This stone is not synthetic sapphire -- what is it?
PostPosted: Fri Feb 18, 2011 2:44 pm 
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Thanks Barbara!

So I know the scratch tests are destructive (and scratchy!) -- that's okay, the stones in question are all extremely cheap and I don't really care if they get scratched up and destroyed, I'm more interested in finding out the answer. But if I understand correctly, you're also saying that they could shatter? Whoa, that's definitely not good -- I'm glad you let me know that could happen! (And certainly this is not a, um, scalable method to a gemstone that's actually worth anything, I'm definitely willing to concede :) )

How would I find out the qualified folks in SB? I would love to know of a good gemologist around here that I could take gemstones to (and yes, I have some I would NOT expose to the scratch test ;) ), but I don't even know where to start.

Thanks again for helping a newbie!


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 Post subject: Re: This stone is not synthetic sapphire -- what is it?
PostPosted: Fri Feb 18, 2011 2:55 pm 
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Try
Robert E. LaPrad GG
Senior Member NAJA
805.682.5358


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 Post subject: Re: This stone is not synthetic sapphire -- what is it?
PostPosted: Fri Feb 18, 2011 4:27 pm 
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Thank you!


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 Post subject: Re: This stone is not synthetic sapphire -- what is it?
PostPosted: Tue Feb 22, 2011 12:45 pm 
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considering the stone looks quite clean, that it was very cheap and was sold as a synthetic, I doubt that would be a natural stone. Some testing would be needed to determine which kind of artificial stone that is (blue glass, blue synth spinel, blue synth corundum, blue synth forsterite, blue synth quartz, blue yag, blue cz...). Could also be a blue doublet.
You could at least start with the loupe.

my opinion: synth spinel


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 Post subject: Re: This stone is not synthetic sapphire -- what is it?
PostPosted: Tue Feb 22, 2011 2:18 pm 
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Hey, thanks! A lot of possibilities -- thanks for helping me see what they all are!

I'll look at it with a loupe when I get home today. I've also thought of investing in a dichroscope, which I don't have yet, because I think that would be kind of fun to play with.


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 Post subject: Re: This stone is not synthetic sapphire -- what is it?
PostPosted: Tue Feb 22, 2011 3:54 pm 
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One can often use the light emitted by a computer monitor to view pleochroism as a computer screen emits plane polarized light.

If you rotates their gem in front of a white screen, pleochroism can be determined.


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