Author Topic: GIA vs AGL for non-diamonds?  (Read 13403 times)

Offline dovesgate

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GIA vs AGL for non-diamonds?
« on: August 26, 2011, 05:56:44 PM »
Instead of hijacking the thread with all the pretty gemstones, I'm putting my question here.

I just bought myself a chrysoberyl ring as a reward for a personal achievement and it is exhibiting some color changing. I want to send it off to a lab to get the stats and whatnot to make sure its not just wishful thinking on my part (and that it's a natural stone not a synthetic) but where should I send it?

I was going to send it to GIA since they are so respected for diamonds. However, if the man who cuts such gorgeous gems says he uses AGL, should I go with them instead?

Also, where can I find out how much it is actually worth? Is there a website or something I can plug in the stats and it tells me what it is worth like I can find for metals like gold or silver?

Offline oldmancoyote

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Re: GIA vs AGL for non-diamonds?
« Reply #1 on: August 27, 2011, 04:09:35 AM »
AGL is a good lab for coloured stones (meaning non diamonds). Just make sure that you get the "right" AGL (American Gemological Laboratories in New York; there are at least another two labs using the AGL moniker; I know nothing about them).

AGL is cheaper and gives much more information upfront on the report compared to GIA, but if you pay for the whole shebang on GIA you do get a LOT of extra materials/info ("analytical report"). Bear in mind that the two grading systems are not directly comparable.

Valuation is a messy thing. For starters, if the diamond market is illiquid from a consumer's point of view, try to sell a coloured stone and come back to tell me... So, do expect to see very different values if you require a resale/estate appraisal vs. an insurance appraisal. Neither GIA nor AGL (the right AGL) offer appraisal services, so you will need to find a competent appraiser too.

I don't know of any website where you can plug in stats and get "valuations", but if I knew of one I would recommend avoiding it, particularly for coloured stones and coloured diamonds. There is so much to consider, and the variation in grading and the breadth of each grade are such that the results would be at best useless, at worst downright dangerous.

Offline Trinkette

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Re: GIA vs AGL for non-diamonds?
« Reply #2 on: August 27, 2011, 01:28:25 PM »
Oh noooooo! I did it AGAIN! Hit the wrong key and the Apple ate my post. Grrrr. I AM an idiot.  :1087:

OK, here's the short version:

Dovesgate, I LOVE chrysoberyl. Congratulations on your purchase. Is your ring newly fashioned or vintage?

No doubt, you know this: chrysoberyl is pleochroic, meaning that the gem shows two or more colors, depending upon which angle you view the stone (actually, chrysoberyl shows three different colors). And, of course, "ordinary" chrysoberyl that shows color-change (specifically, it displays different colors in different lighting sources) is known as the "extraordinary" variety of chrysoberyl called alexandrite. Interesting that you have a gem identified as chrysoberyl that shows the more rare, coveted (and expensive) charactersitic of alexandrite. What color is your gem in daylight? Incandescent light?

Personally, I have no direct experience with AGL, although I know several gem cutters and dealers who respect the lab. I am sure they, and OMC, know best. That being said, I'd wager a guess that no US lab has more resources at their disposal than GIA... if you need them (and don't mind paying the price).  For what it is worth, I think magnification is the only way to distinguish natural chrysoberyl from manmade. Also, a lab will be able to identify the specific chemical properties of your gem.

I hope we get to see a pic of your new ring one of these days!

« Last Edit: August 27, 2011, 01:29:27 PM by Trinkette »

Offline dovesgate

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Re: GIA vs AGL for non-diamonds?
« Reply #3 on: August 27, 2011, 02:24:35 PM »
It has a vintage look to the setting but I think its a modern vintage look. White gold halo with itty bitty diamond chips, milgrain edges. I should have taken pictures before having the chrysoberyl removed.

I bought her thinking she was a regular green yellow. When I first saw her under store lighting, she was a vivid green yellow. When I took her to work, she was ranged from a medium to vivid yellow then olive green and a bit of light orange in the middle in the car on the way to get her removed. Right now she is sitting in her bag on my computer desk and she's light green and orange.  Its possible she is just picking up colors around me right?

I borrowed my husbands' phone and took some shots of her sitting on top of her setting in different light. Let me upload them and I will post them and hopefully you guys can tell me if you think its a good idea to send it in or just save my money.


Offline dovesgate

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Re: GIA vs AGL for non-diamonds?
« Reply #4 on: August 27, 2011, 02:45:30 PM »
Here's her orange and green. She got brighter colored when I moved her closer to the sunlight coming through the window behind me.


Outside on my front porch


Also on my front porch but with my back to the sunlight.


Flourescent light bulb in my kitchen and a lemon-lime color.


Lighting in my bedroom. It's an energy saver light bulb and this is where she looked vivid pure yellow to me. Not sure if it came through on the photo very well


« Last Edit: August 27, 2011, 02:50:31 PM by dovesgate »

Offline dovesgate

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Re: GIA vs AGL for non-diamonds?
« Reply #5 on: August 27, 2011, 02:48:06 PM »
LOL please ignore the chipped nail polish and the weird looking prongs. She is just sitting on the setting since I planned to send her off.

Offline Trinkette

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Re: GIA vs AGL for non-diamonds?
« Reply #6 on: August 27, 2011, 02:48:43 PM »
The colors you describe are exactly the colors one would expect to see from a green-yellow or yellow-green chrysoberyl: ie, depending on how you are viewing the gem, one would expect the pleochroistic nature of a chrysoberyl to exhibit versions of its body color, sometimes more than one at a time. In this case, green, yellow and orange (sometimes the orange is brown lucky you, your orange is more desirable than unloved brown). Perhaps, the "color change" you have been experiencing is really the effect of pleochroism, not, actually color change, as defined by gemologists.

Offline Trinkette

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Re: GIA vs AGL for non-diamonds?
« Reply #7 on: August 27, 2011, 02:50:22 PM »
I posted while you were posting. I haven't seen the photos yet (they are still loading)...

Offline Trinkette

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Re: GIA vs AGL for non-diamonds?
« Reply #8 on: August 27, 2011, 03:02:57 PM »
Pretty gem, I really like its color, shape and size. Really, it is impossible to tell about the color through photos... My GUESS would be that you are seeing the effects of pleochroism, and the effects of different lighting conditions (intensifying or subduing the individual colors), not "color change." But, to know definitively, there are the labs...  ::)

Offline Trinkette

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Re: GIA vs AGL for non-diamonds?
« Reply #9 on: August 27, 2011, 03:05:17 PM »
Did I mention that chrysoberyl is one of my all-time favorite colored gemstones?  :devildance:

Offline dovesgate

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Re: GIA vs AGL for non-diamonds?
« Reply #10 on: August 27, 2011, 03:14:29 PM »
See, this is why I come here and ask my stupidity-revealing questions. I've never heard of pleochroism before. To me, a stone is a stone is a stone and then it turns colors and I say "what the heck is this?!"

You're totally right Trinkette. I googled "pleochroism" and one of the results told me to hold it up to my monitor because computer screens emit plane polarized light.

So, I rotated it in front of the white screen like it said and voila! All three colors popped up. I think I'll just save my money on the lab certificate and enjoy her for what she is.

Offline lovecolor

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Re: GIA vs AGL for non-diamonds?
« Reply #11 on: August 27, 2011, 03:31:45 PM »
I think that's a wise decision, Dovesgate...It's a cool color stone and I love the shape of it.  Enjoy it!  :love7: