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 Post subject: Fluorescence in Star Ruby and Ruby-indicators of synthetic
PostPosted: Sat Nov 23, 2019 3:41 am 
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Joined: Mon Nov 18, 2019 7:29 am
Posts: 16
Good morning to all,
I have several questions after scouring through many interesting threads on here about fluorescence in various country origin natural Rubies along with ff/treated/heated/synthetics.

1. There is an old GIA video lecture online from 1988 on "How to Separate Natural from Synthetic Ruby". The lecturer at one point states that if you see a very strong/extremely strong fluorescence in long wave uv and a "pretty good" in sw, " I would say it's a "synthetic".

What exactly has happened between 1988 and current time in technological advances in equipment and detection of "synthetic"?
How "strong" of a fluorescence are we talking about that should make one suspicious?

I've looked at side by side photo/video comparisons of different treated/filled rubies vs. untreated and it's not that easy to always see the difference in degree of fluorescence! I have a natural Thai ruby that's not fissure filled but I don't know if it's received heat treatment or other type, but it barely fluoresces. I have a Burma ruby that is also a natural ruby non ff (heating unknown) and it glows hot pink under uv.
When you've got gem purveyors like Gem Shopping Network online ooooing and ahhhhing clicking that uv light blowing up Rubies (and they don't sell glass ff/synthetic) how does one nowadays judge the line on "very strong/extremely strong fluorescence? I've seen closeups of natural but heated no glass fill rubies that knock your socks off they're so bright under uv, and they're very small stones.

I understand that the "only way" to determine any/all treatment/heating/synthetic is either know your way around a microscope etc, or send off to a lab, but what of real note has changed since 1988 regarding using fluorescence as a "tool" combined with other tools (besides nothing/everything?).

2. Does all of the above on fluorescence also apply to Star Ruby?
Interesting reading here:
viewtopic.php?f=37&t=2371
viewtopic.php?f=6&t=2546
I have a weakness for large star cabs and have many that fluoresce like heck on fire. They are all pale grayish deep to light purple with obvious hexagonal structure, inclusions and pits under magnification, and did not break the bank. I can't imagine anyone would bother to glass fill/beryllium these as they certainly aren't perfect looking end products close up, but oh yeah, they fluoresce brightly hot pinkish red, and some have 6 pretty long legs under directly pointed normal light, though not a great vivid color or even partially translucent stone. I know the obvious "Linde" fake star look, but hadn't even dreamed my cabs could be treated/heated Star Rubies. ARGH!

I tend to buy "imperfect" visually close-up view, if I can't go hands-on, because am pretty sure and willing to gamble I'm getting a natural stone. I would rather have something "not perfect" - but beautiful (to me) - than something treated/glass filled. I keep an eye out for overlooked old cab star rings set in early 60's - 70's hippie days jewelry, either this grayish lilac-purple or pinkish red. Precisely because they aren't perfect looking color, and you can find some honkers. Latest was an 18mm x 22mm cab vintage ring in a nice but ratty looking pierced work silver mount listed as a "Labradorite". Not with that hexagonal structure and 6 leg star.

Does anyone know about when glass filled/heated/beryllium really started showing up in cab stars? And am I correct to call my purplish cab collection Star Rubies? Would it be fair to say that opaque colors in the grayish purple are "safer" bets you might be purchasing an untreated unheated star since no one tried to nudge it towards pink/red/blue/ the value wasn't there to do that in a stone that would never hit a blue or pinky red? There's so much technical information in here; I've got a long learning curve ahead - I'll keep digging! :shock:


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