Could Synthetic Sapphire test as Spinel??

[wakingdreams53]

I was searching for a setting similar to Charmypoo's imperial malaya split shank and this was one of the results:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=180651848425&ssPageName=ADME:X:RTQ:US:1123

Obviously not the ring I was looking for but I was intrigued. Before the seller changed it to what it is now (after I asked) it said: Main Stone: Amethyst. Mkay, so they've got sapphire, spinel, and amethyst all in the same ring. I had to bug them.

They answered: I corrected the one on the short description..... not amethyst as you can see! It tests as "spinel" on my presidium gem tester so....hence the description. And as you can see by the price I am assuming faux sapphire.

I know blue spinels cost a LOT, and this may be a steal if it really is spinel... which is doubtful. But anyway, back to the question at hand. Could a gem tester mistake a synth sapphire for spinel?

 

[whatmeworry]

It's probably testing correctly as a spinel, but blue synthetic spinels are really cheap so you should base the pricing assuming it's a synthetic spinel. Now if it turns out to be natural ...good for you.

 

[innerkitten]

Lab spinel could.

 

[T L]

I was searching for a setting similar to Charmypoo's imperial malaya split shank and this was one of the results:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=180651848425&ssPageName=ADME:X:RTQ:US:1123

Obviously not the ring I was looking for but I was intrigued. Before the seller changed it to what it is now (after I asked) it said: Main Stone: Amethyst. Mkay, so they've got sapphire, spinel, and amethyst all in the same ring. I had to bug them.

They answered: I corrected the one on the short description..... not amethyst as you can see! It tests as "spinel" on my presidium gem tester so....hence the description. And as you can see by the price I am assuming faux sapphire.

I know blue spinels cost a LOT, and this may be a steal if it really is spinel... which is doubtful. But anyway, back to the question at hand. Could a gem tester mistake a synth sapphire for spinel?

Not all blue spinel is expensive. Very dark stones with average saturation, like the ones appear in the photo, are not pricey. In fact, you can find them all over ebay for very little, and those are small too, at about a half carat each. Considering it's 10K gold, I think it's fairly priced for a pre-owned piece.

 

[wakingdreams53]

Hmm, awesome food for thought! Thank you all!!

 

[Pandora II]

I would guess that it's synthetic spinel. If you can get a light behind it, a spectroscope should tell you for sure. Do you have access to UV light? If so, what happens?

I'm very wary of those gem testers as there is huge scope for error - dirty stone, ambient temperature, stone temperature, how many times in a space of time you test the same stone, how hard you press, how the tester is held, where on the stone you touch - possible inclusion/filler rather than the stone itself etc. I had a play with a couple a few months ago with a box of known samples and the results were all over the place depending on these factors. They're best for diamond melee IMO.

 

[stylish1]

The fact the gold in the ring is only 10kt. raises a small flag I think. Still a good looking ring. Usually spinel is single refractive if I remember.

 

[Pandora II]

The fact the gold in the ring is only 10kt. raises a small flag I think. Still a good looking ring. Usually spinel is single refractive if I remember.

Like garnet and diamond, spinel is singly refractive.

A polariscope will tell you which it is, although it might be tricky with the setting, and spinel shows 'tabby extinction' under the polariscope whether it is synthetic or natural (although tends to be stronger in the synthetic) which might throw people if they're looking for the 'remains dark through 360 degrees' that the text books can say for SR stones but rarely seems to happen in real life as so many stones have anomalous strain.

So, for that reason I'd opt for the spectroscope as this will separate the synthetic from the natural. Flame fusion synthetic spinel (probably 90% of synthetics) also has a higher refractive index than the natural - generally 1.730 as opposed to the 1.718 ish of the natural. You might also get a bright red under a Chelsea Colour Filter or a reaction with SW UV.

 

[chrono]

No, a synthetic sapphire will test as a sapphire, while a synthetic spinel will test as a spinel. Both synthetics are inexpensive and with natural stones, pricing runs the gamut as well from inexpensive to very expensive, depending on the colour quality.