Jewelers and gemologists: A question about Amethyst

[Spectre of Pithecanthropus]

I recently acquired an amethyst ring. At least it's supposed to be, but the stone looks so good that I suspect it of being a violet CZ. I'm pretty sure that it's not synthetic corundum because it shows no reddening in sunlight, but the luster of the stone is superb, as is its general brilliance effect. This is especially noticable
with point sources of light. There is no noticeable pleochroism.

As far as its color is concerned, it's just your typical
amethyst purple, and I'd say it's several carats. I don't know the name of the cut, but I've never seen it before on an amethyst. It's basically rectangular, but has a lot more
facets than a standard emerald-type step cut.

Can anyone help me confirm that this is an amethyst?

[wring]

Jeweler's daughter speaking - I would suggest taking it physically in to a reputable gemologist. I doubt that anyone could confirm from a description. My two cents.

[tygre]

Take it to a licensed gemologist. CZ is harder than amethyst, and has a different refractive index, so they should be able to tell you for sure pretty easily.

I have seen some *really* nice amethyst, so it's not impossible that it is amethyst.

--tygre

[Spectre of Pithecanthropus]

Originally posted by tygre
Take it to a licensed gemologist. CZ is harder than amethyst, and has a different refractive index, so they should be able to tell you for sure pretty easily.

I have seen some *really* nice amethyst, so it's not impossible that it is amethyst.

--tygre
I know, that's one nice thing about amethyst. Even though they're cheap stones, good ones can be stunning. In this case I think the cut is probably a factor, too, and it could also be that I've never seen one that before that had just the right depth of color and clarity as this one does.

Wring, could you ask your parent if they he/she can tell me
the name of that cut?

[Gaudere]

Jeweler's daughter here as well, and sold jewlery for about eight years. The purple CZs I have seen are rather pale and do not approach the color of a good amethyst. You may have a synthetic amethyst--genuine amethyst, but manmade instead of mined and therefore often much higher quality. Synthetic amethysts are sometimes unfortunately found in a batch of mined stones, and since they are so inexpensive it is not cost-effective to test them in all but the most expensive stones (some Siberian amethysts can run thousands per carat). Synthetic amethyst can be very difficult to distinguish as well, though a couple indicators are a remarkably clear stone (check under magnification) and lack of "color zoning" (a natural stone without some color variation through the stone is rare). Twinning used to be used to distiguish synthetics, but that's not as common for synthetic amethysts anymore. Like wring said, I'd recommend a gemologist of you really want to know.

The cut sounds like a cushion cut to me, but it might be a custom job.

[Gaudere]

Correction: I meant to say a *lack* of twinning was once used to distinguish synthetics.

I dug up some URL's: here's one on picking out synthetic amethyst. http://www.jckgroup.com/archives/1998/01/jc018-160.html#Anchor-This-28897

Here's a few pics of the cushion cut: http://www.vvtv.com/famdetail.asp?familyID=Y14426
http://www.gemstoneworld.com/jewlshop/images/kunz1.jpg
http://www.planetarygems.com/_borders/goldenunheated252.jpg

(it's not a very standardized cut, so you get a fair amount of variation)

It may also be a radiant cut: http://www.planetarygems.com/_borders/extra_fine_damburite_6.95.jpg

[Spectre of Pithecanthropus]

Originally posted by Gaudere
Some Siberian amethysts can run thousands per carat).
Amazing! I always understood that before the Brazilian deposits were found, amethyst. was quite expensive, but ever since the Brazilian producers flooded the market, it's been so cheap that it isn't worth synthesizing. Though I will
say that the difference between the mediocre- and top-quality Amethyst. is striking. I also have a loose trap-cut amethyst; it has a rich purple hue with red highlights--here again, based on the responses I've seen here, I almost can't believe that it's a genuine mined stone. I paid about $40 for it, but it was a long time ago.

[Gaudere]

Well, *most* mined average quality and sized amethysts are only about $10 per carat wholesale (if I remember my pricing correctly; it's been quite a few years), while synthetics are a couple bucks for the same weight. The thousand-per-carat ones I mentioned are exceedingly rare; even very large excellent amethysts are ususally only a couple hundred a carat. Apparently synthesizing is cheap enough that it's worthwhile for unscrupulous sellers to salt their amethyst lots, although by this point there's enough synthetics being passed around as genuine that a honest jewelers can quite easily sell a synthetic as genuine all unknowing. It's not really worthwhile to test a stone if it's only a couple bucks to you, so synthetic amethysts can get sold again and again without anyone finding out.

[Chronos]

Amethysts are $10 a carat? Then what the heck was that fist-sized chunk of purplish-blue crystal I bought for five bucks a few years ago? It appeared to be a fragment of what once must have been a huge geoid, and seemed to have about the right crystalline structure.

[Gaudere]

Mined, cut, jewelry-grade half- to three-quarter carat ames go for about 10 bucks a carat *wholesale*, if my prices are still correct (don't have the gembuying catalogues anymore, and it's been a few years). What you bought probably was an amethyst (which is simply quartz, after all), but uncut and likely not of jewlery-grade color or clarity, so it's quite a bit cleaper. Heck, I can pick up 20-carat polished ames for a quarter or so at some stores, but it's just that they're nowhere near the quality required for jewelery and they haven't been cut, just tumble-polished. You can buy uncut stones fairly cheaply--even star sapphires and rubies--though they're usually *abysmal* quality. They still can be very pretty, but they're not gem-grade. Five bucks was probably a pretty good deal, although you never know, it could've been a synthetic; they have the same crystalline look as the naturals.

[don willard]

Jewellers charge so much for testing stones that seldom does anybody have anything tested. The industry prefers that the general public be kept in total ignorance. People who know things about things are dangerous. When you go into a jewelry store or to a dealer, you seldom find one that knows that jewels are made out of minerals--elements, atoms, and if they know this they say they don't know the exact content, etc. When you watch jewel sales shows on tv you can tell they don't have this concept of what they are made out of. Only occasionally will you hear or see the mineral information. If you listen carefully, they sometimes use terms like "created," which means what synthetic used to mean, namely the actual mineral. They get some aluminum oxide from someplace and heat it up so that it crystallizes into a big crystal. By adding a few atoms of other minerals, they can get colors, and thus make rubies and sapphires, which are superior to the ones found in nature and cheaper. People don't want them because they aren't "real," but they are as real as the ones formed by nature in caves or wherever, and they are flawless. Aluminum oxide is aluminum oxide. Emerald is beryllium aluminum silicate. Of course it matters how the atoms of the aluminum and the oxygen are related to each other (what crystal structure they are in). I got a beautiful large stone from a man who had cut it who, however, knew nothing about mineralogy, since he said the material was "synthetic aquamarine." Aquamarine is the same material as emerald, with slight differences in a few other minerals that have crept in to make the color difference. They don't make man-made, created, or synthetic aquamarines, they use created spinel, which is magnesium aluminum oxide with extra magnesium.
The main minerals they man-make colored stones with are corundum, which is aluminum oxide, and spinel.

At some gem shows, especially those sponsored by local rock and mineral clubs, you will see people demonstrating stone cutting. A piece of glass from a cola bottle, for instance, can be cut beautifully but are seldom for sale. This illustrates what can be done by careful,skilled workers. Careful skilled workers are found only in third world countries, for the most part, and if they are found here or in any urbanized situation, they charge a lot of money. There are a lot of gemstones out there, natural and "created," and mostly poorly cut.

Find that show they had on PBS about how the diamond industry talked women into having to have diamonds, when before this happened they had any kind of nice stone for an engagement ring, and you'll get an idea of what's going on.