Well, here I set with egg upon my face . You’re right … and
this points out why I should not post to newsgroups late at night …
sigh … I went back and checked my notes … the fluorescence I
noted was in synthetic CARBORUNDUM not QUARTZ … duh!
This came up when I encountered a rough dealer with a table full of
"river tumbled sapphire rough" that was suspiciously homogenous in
color and hue … not to mention priced well below market price.
Looks like they have taken to smashing up synthetic boules and tumble
polishing the chunks to simulate natural gravel. What is real cute is
how their English comprehension is inversely proportional to the
depth of questioning. This particular fellow would not admit the
rough was synthetic, but he became less than comprehensible when I
wanted written documentation of origin and source. 'Nuff said!
BTW, even that is not completely reliable of late … I did a quick
check on some boules I received from Morion and of 6 splits, the
white (clear) and light pink do not fluoresce (1 each) …
Back to the microscope and yep … very careful inclusion
examination … what is particularly frustrating is most amethyst is
not particularly high priced relative to other colored gemstones …
where do you give up? Paying GIA inspection fees that can approach
half or more of the stones value sure isn’t a good answer.
I must tell you that if you get youself a GemLite UV light or
something close and you get yourself a natural stone and then this
MAN-MADE material you will see just what the GIA says is the best
way to tell the differnts between the the natural and MAN-MADE
mateiral. For a written artical call “Gems and Gemology” and
Colored-Stone. There is only one way to be 100% sure and that is toi
send it to a GTL but you can be 98% with a few simple test. If you
have gotten your GG from the GIA in the past 2yrs you know how to
tell the differnts with only a the GIA’s " Basic Gem ID kit" the key
is the UV light and the SG is differnt. I sell the VERY BEST
MAN-MADE Amethyst in the world and I have to make sure that I do not
confuse the Natural with the Man-made. But just like with the very
BEST MAN-MADE diamonds the UV light will show the true from the
MAN-MADE.
I am going to try and take some photos of the reaction to the UV
light of natural amethyst and the a couple of differnt Man-Made
amethyst stones. Since some people will not do this for themselfs I
will do it. I just need to know how to send them to ganoksin so that
everyone can see. I will also get the Book, Chapter and Page from a
guy I know that has just finished his colored Stone ID course for
his GG so I can post it on the digest also. SO all the people who
say there is no test will see what the GIA is teaching GG’s on how
to hell the differnts. This is not that hard folks. When a person in
this business say " YOU CANNOT TELL THE DIFFERNTS. OR IT IS
IMPOSIBLE TO TELL STONES APART." They have yet to learn the test or
they are hidding something.
William, I am most interested in this technique as I am one who has
never heard of it before. Please refer me to which issue of Gems &
Gemology in which I can find this article. I am also interested in
about Ultraviolet Spectrophoptometers and Infrared
Spectrophotometers. Amethyst identification is a problem when you get
to the really fine qualities of amethyst. When you are selling
amethyst at $30-$75 per carat you really need to be sure that the
stone is natural and not man made. I have a market for amethyst in
the 50-150 carat sizes in extra fine quality. These stones must be
10X clean, exhibit no color zoning under 10X, or 10X visible twining.
I have looked at a lot of cut stones and rough and honestly can not
tell the difference in the finer qualities. I would like to know how
GIA tells the difference or how any gemstone laboratory tells the
difference. Respond to me off ORCHID if you do not want your
message posted.
Just working on my gem id’s tonight and doing some reading. Wayne
Emery said in a previous post about seperating natural and synthetic
amethyst:
Actually, the test is quite simple. A polarizer is used to
determine the presence/absence of polysynthetic twinning. Almost
all natural quartz exhibits polysynthetic twinning; synthetic only
very, very rarely.
I am still a newbie to gemology and I am sure you have way more
experience than me. But I did want to share what my GIA text says on
the subject:
"In the past, most synthetic amethyst was untwinned. It
commonly showed a "bull's eye" optic figure and broad bands of
interference colors without the angled pattern seen in
Brazil-law twinned natural material. These differences made
identification practical. However, laboratories eventually
began producing twinned synthetic amethyst, and this new type
of synthetic became commercially available on the market. The
result of this development was that the task of identifying
synthetic material got tougher. However, there was still a
difference between natural and synthetic that a gemologist
could count on: The interference color patterens of some
twinned synthetics were angled more narrowly than those in
natural amethyst's Brazil-law twinning pattern. The acutely
angled bands in these lab created amethysts resembled a
flame-like pattern that does not occur in natural amethyst.
Today, however, identification of synthetic amethyst is not
just difficult- in many cases it's impossible to separate
natural from synthetic material using standard gemological
tests. That's because advances in synthsesis technology have
ushered a new type of twinned synthetic amethyst into the
marketplace. The new twinned synthetic mimics both the
interference color patterns and the optic figures of natural
material. So the presence of Brazil-law twinning under crossed
polaroids no longer means that a stone is natural, since
today's synthetic amethysts can now show this same
characteristic. Synthetic amethyst can now also display color
zoning similar to that of natural amethyst. These new
developments in synthesis technology have made the standard
gemological tests for identifying synthetic amethyst obsolete
unless there are diagnostic inclusions." -GIA
I hope this info is helpful. Sounds as if the synthetics are quite
prevelant and are getting harder to catch. I would still look for
twinning. But not base my id soley on that.
I wan to thank you for bringing me up to date on the synthetic
amethyst situation. Indeed, I just checked a kilo size crystal of
syn amrthyst and it does display polysynthetic twinning. Although
it’s not quite the same look as natural, or, at least, all the
natural I have seen. This crystal also has some prominent color
banding in it, although I’ve seen that for some time. This material
is from the labs at the Russian Academy of Natural Sciences,
manufactured within the last 60 days or so. I think the Japanese are
making lots of syn quartz, maybe theirs is twinned like the natural.
Thanks, I’ll spread the info amongst some other cutters!
I am glad the info on amethyst was helpful. I hoped it would be.
Amethyst is such a popular stone. And it sounds as if synthetic
versions can pop up anywhere.
As I said, I have a lifetime of learning ahead of me in this area.
Today I struggled a bit with deciding if an emerald was natural or
synthetic and if a sapphire was natural or synthetic. The sapphire
showed pleochroism through the table which was suspicious. But it had
straight zoning and a very fine fingerprint inclusion that lead me
towards natural. So tricky, giving me mixed signals!
Thanks-Carrie Nunes
(PS: The text I took that amethyst info from is the Gem ID 28 course I
am taking. They have a new updated Gem ID course coming out anytime
now. It is supposed to come with a DVD and you end up testing twice
as many stones as the current course. Seems to be new info coming
out all the time.)