Anyone know Alexandrite?

[chrisiknow]

When tearing out the walls of our cottage my fiance found an old cowboy
bolo with a rather large amethyst slider on it. Recently, I decided to wear it to work, and discovered that it is not an Amethyst...it''s a natural Alexandrite! What a find.

It is in mint condition, with excellent clarity and fire. The stone is a 12mm round cut and the color range is from bright fuschia to a blue gray. Not sure of the carat weight.

Anyone have any ballparks on what it''s worth?

 

[Colored Gemstone Nut]

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On 3/21/2004 12:20:21 AM chrisiknow wrote:





When tearing out the walls of our cottage my fiance found an old cowboy
bolo with a rather large amethyst slider on it. Recently, I decided to wear it to work, and discovered that it is not an Amethyst...it's a natural Alexandrite! What a find.

It is in mint condition, with excellent clarity and fire. The stone is a 12mm round cut and the color range is from bright fuschia to a blue gray. Not sure of the carat weight.

Anyone have any ballparks on what it's worth?
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Hi Chris:

Alexandrite is considered a transparent gem which appears green in the daylight and red to purplish red in artificial light (indoors) . This phenomenon is known as color-change. Alexandrite is strongly trichroic (phenomenon of different colors appearing when viewed from 3 different directions)There are variables which affect the price of this gem including how dramatic the color change is, modifying colors, size, and location Alexandrites are found. When the color change is dramatic, the stone will be very expensive. Less expensive stones will have a weaker change and less saturated colors. The color phenomenon is a result of the presence of chromium ions and the way those ions are absorbed and reflected. The presence of brown or gray modifying colors will lower the value vs. the price per carat on alexandrites with the lack of these modifying colors. Alexandrite is more common in smaller sizes but still fetch a steep price tag due to the rarity of the gemstone and the current command in the market.

I would caution you when assessing the authenticity of the piece. If this is a real alexandrite, it is worth quite a bit of money depending on the color change, saturation and clarity. There are many imitations and synthetics which range from color change sapphire, spinel and synthetic alexandrite which is actually a synthetic form of corundum (sapphire) which has been treated with vanadium to give the synthetic stone it's color change affect.

In any case I think it is paramount for you to get the stone assessed by an independent appraiser who is a knowledgable gemologist.../idealbb/images/smilies/1.gif

Good luck and what a neat find...

Do you have pic's?

 

[valeria101]

The range of color you mention indicates synthetic alex to me... sorry to put it this way. Any jeweler could easily identify the stone.

Here's a webpage with some examples you may find helpful: WWW

The Amethyste-like appearence is very uncommon in natural alexandrite.

 

[Richard M.]

Given the size, colors and probable age of the stone, it has all the hallmarks of flame-fusion synthetic corundum that's been doped with vanadium to exhibit color change. The colors are wrong for natural alexandrite. A 12 mm. natural stone with top clarity would be very valuable and not likely to be worn in an everyday bola tie. A simple refractive index test may be all that's needed to ID it.

If the R.I. tests for chrysoberyl instead of corundum, take it to a qualified gemologist who'll be able to do more sophisticated tests to make the determination between natural alex and synthetic.

Richard M.

 

[fire&ice]

I would tend to agree w/ the others. A natural alexandrite in this larger size is rare. Most that I see in that size are sythethic alexandrites. Quite pretty, but not in the same league price wise.

This size synthetic alexandrite in this type of piece of jewelry is quite common. Natural ones are not.

 

[mogok]

Yep I agree with Richard...
Anyway if its really a natural alexandrite, so that's a real find!
Are you sure about it?

Some natural inclusions? Chrysoberyl refractive index?...

 

[chrisiknow]

I think you guys are probably right. Anyway, the up side of finding out that it's synthetic is that I will keep and wear it, as it is quite a beautiful stone. If it was natural I would sell it.

I keep trying to compare it visually to my natural alex, and I'm getting a headache. Inclusions in it are tiny bubbles, (or they may just be bits of vegetable matter.)
Then there is a very thin cloud that covers almost 1/3 of the stone like a phantom. Both of the above are only visible under magnification.

The thing that makes me think it's probably synthetic is that it's response to artificial light is very magenta, not red and it becomes fiery. In sunlight the stone loses all brilliance. It turns a grey blue with purple rather than aqua.

My thoughts that it might be natural stemmed from the fact that the cottage we tore down was built in the late 60's.
And they were still somewhat common back then. In any event, the piece itself draws a contrast to mind: What kind of cowboy is going to buy a natural or synthetic Alexandrite,anyway?

I'd like to test it's refractive index for chrysoberyl. I live in a remote area. Where do I go to get this done?

Thanks for all your expert advice! I'll keep you posted.

 

[Richard M.]

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On 3/23/2004 3:42:14 PM chrisiknow wrote:


I'd like to test it's refractive index for chrysoberyl. I live in a remote area. Where do I go to get this done?

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Unless you know someone who owns a refractometer I think your best bet is to check the Yellow Pages for jewelers who offer gemological services. Phone around and explain all you need is an R.I. test and why. You'll likely find someone who will do the work for a small fee. Since the R.I.s for corundum and chrysoberyl can overlap slightly the test will have to be done carefully. Other possibilities include flame fusion synthetic color change spinel and glass simulants. Both should be easy to distinguish from chrysoberyl. If the stone tests as chrysoberyl then you're faced with an interesting situation in my opinion. If you're sure your stone dates from the 1960s you'll be happy to learn that the first flux-fusion synthetic alex wasn't developed until 1973 by by Creative Crystals Inc. of Danville, Calif. Good Luck!

Richard M.

 

[mogok]

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On 3/23/2004 3:42:14 PM chrisiknow wrote:

Inclusions in it are tiny bubbles, (or they may just be bits of vegetable matter.)

Then there is a very thin cloud that covers almost 1/3 of the stone like a phantom. Both of the above are only visible under magnification.
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Well if you have a cloud of very tiny bubbles that cover a 1/3 of the stone then its probably a synthetic corundum imitation of alexandrite. This inclusion is typical from flame fusion synthetic corundums. May be if you check well with the loupe in all the direction turning stone stone over a diffused light source (for exemple a maglite coverred by a white tissue) then you will be able to discover some "curved striae" that are the proof of the synthetic origin of your stone.
Anyway, there are no bubbles in natural alexandrite,... and a cloub of tiny bubbles is the proof or a synthetic origin.
All the best,