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Blue star sapphire question


#1

H All;

A number of years ago I was at a gem show and saw a "denim blue"
star sapphire. From the start, I figured this to be a diffusion
treated stone, but the color was so intriguing and the price quite
reasonable, so I bought it, thinking I might just make a ring for
myself with it some day if nothing else (I’m not particularly put off
by the treatment but the psychology of selling treated stones
requires subtleties I may not have mastered, if you catch my drift).

Shortly after, I saw that a fellow jeweler I know had bought one
just like it but slightly different in size and proportion. The two
stones were indistinguishable except for the size and shape. Today he
called me and told me a gemologist had looked at it and declared it
was a lab grown star sapphire that had been doctored and diffused to
look real. I told him I would bet he was wrong. I’m no gemologist,
but I get around and I’ve been looking at gems for decades. I also
don’t have instant faith in anyone claiming to be a gemologist. I
just had one in my shop, GIA trained in colored stones. I asked her
opinion on what I believed to be a small padparasha I had bought from
a customer cheap. I didn’t tell her I had already tested the
refractive index and observed pleichroism with a calcite dichroscope.
She said it might be a tourmaline… really? Even lab grown
padparasha can’t quite pull off the ambiguous, pink to orange color
which reminds one of Mercurochrome and mine does that. The
refractive index of sapphire and tourmaline aren’t even close. I just
nodded and said, “hmm, I’ll think about that.”

So here’s what I observed about the blue denim sapphire I have,
which is like my friends. It’s fairly even in color, has a 6 point, 3
axis star, it’s rough and uneven on the bottom, but the bottom has
very suspiciously even consistency to the grain. A chink or two makes
it look genuine, not like the shiny, smooth bottom of a Linde (and
obviously no “L” etched on the bottom). When a light is shined on it
and moved in a circular pattern, the star follows the light. You can
see this effect in a Linde, but it’s not as pronounced. On a Linde,
the star is quite distinct whereas on my stone it’s softer, more
diffused. Close examination reveals flaws and fissures breaking the
surface, minor but looking like a natural stone, not perfect like a
lab grown. The star is slightly off axis to the oval cut, unlike a
lab grown which is perfect, but this could be achieved by re
cutting. The oval shape is not a calibrated proportion like 7 X 5,
etc, it’s more like 17 X 14 or something. Again, re cutting could do
that.

Now I know about the trick of heating an quenching lab grown
corundum, then glass filling it to dupe good color cabbing material,
but this shows no evidence of filling and I’ve never heard of this
being done to star sapphire.

OK, welcome any info or opinion on this.

David L Huffman


#2
I also don't have instant faith in anyone claiming to be a
gemologist. I just had one in my shop, GIA trained in colored
stones. I asked her opinion on what I believed to be a small
padparasha I had bought from a customer cheap. 

I do not have instant faith in Gemologists either, and I am one.
When you go to a competent doctor, they do some tests to diagnose
what is causing your discomfort. They do not guess. When your car has
a ticka ticka sound, a competent repair person does some diagnosis to
determine what component is making the noise. They do not guess.

Gemology is not about opinion. It is a scientific approach that
determines what it is by eliminating all the things it cannot be.
When a customer tells me who said what, I am a “doubting Thomas”, I
do not believe a word of what anyone else says unless I can
determine what what a gem is based on scientific evidence. There is a
tremendous amount of misspread by “jewelers” and
unfortunately, by Gemologists.

In this day and age, only a fool would site ID. The treatments and
processes used to enhance gems makes Gemology a veritable minefield
that can cause you to lose credibility in your community. It takes
years of experience to have reasonable certainty of what something
is without testing, but thinking I know what something is and
committing to state with authority to a customer is not something I
am willing to do, ever. I never answer unless I am 100% sure and I am
willing to stake my reputation on what I say. I do not make an ID
unless I know I cannot be proven wrong. This is a business built on
trust.

I am fortunate. Neil Beatty at americangemregistry.com has his
business here in Denver, and he is my go to guy for Gemology
questions when I am not sure. He is who I would recommend for
identification and evaluation of what a gem is worth.

4 1/2 months, eight hours a day, five days a week, at G.I.A. gave me
a lot of hands on experience. 33 years later, I still do not jump to
conclusions.

I can tell my customers, and have, that any jeweler who can tell the
color grade of a diamond without using color grading test equipment
is not to be trusted. I cannot do it, and I do not know anyone who
can. If you do not know, keep your mouth shut, you gain more trust
by not knowing than by one wrong answer.

Richard Hart G.G.
Denver, Co. 80210


#3
OK, welcome any info or opinion on this. 

Nothing you’ve described would diagnostically show synthetic or
natural origin. Note that the Linde stones have been out of
production for decades. The stuff seen now is more varied, and
generally somewhat different in appearance. Usually slightly less
"opaque", ie more transluscency to the stone with a little less silk,
but this can vary a lot from stone to stone. In some, the silk is
unevenly distributed. Cutting tells you nothing, as any lapidary can
cut the rough (which is available as such) in whatever manner,
botched or right, as he/she chooses. the think to look for are curved
striations/growth lines. Or, alternatively, straigh growth lines or
those with distinct angular (120degrees) corners in them. the former
are the flame fusion synthetics, the latter, might be natural. But
the biggie in what you mention is price. You said your nice denim
blue stone was relatively cheap. What do you mean by cheap?
Synthetics are cheap. Good looking natural star sapphires are not.
But the distinction between cheap and not varies between people, some
of whom might think anything under a couple thousand dollars to be
cheap, and others who might figure anything over twenty bucks to be
costly… What does your stone weigh, when did you buy it, where did
you buy it, and what did you pay? Tell me that, and your price would
be a better suggestion (but still not actually diagnostic).

Oh, and as to that padparadsha sapphire. Maybe you haven’t, but I
HAVE seen synthetic sapphires, or rather diffusion coated ones, that
were very close duplications to the ideal colors of the natural
padparadsha sapphires. And I’ve also seen tourmalines that, at first
glance, were in the same color range. Dichrosim is visible in both
materials, and might be somewhat similar. The actual refractive index
of course separates tourmaline from sapphire, but you didn’t say if
she had access to that info. By eye alone, it isn’t always clear.
Tourmaline is one of the most variable stones out there. One a few
colors don’t exist in the stuff. And lab grown verus natural isn’t
something you tell by eye with the sapphire. A good microscope, and
perhaps with some, spectroscope, can be needed.

Also, if she just took the GIA colored stones and gem Id classes,
then she’s not yet a gemologist. Only part way through the course
sequence.

And there’s a big difference between someone who’s just yesterday
finished a few GIA courses, and someone with the GG diploma under
their belt as well as ten or twenty years worth of actually using the
info. Kind of the same as with any sort of technical training. New
grads have lots of raw knowledge crammed into their heads, but may
need at least a few years of letting it cook in there, ie experience,
before their real grasp of the has matured. Don’t lump
your whole impression of gemological training into one impression
based on one off the cuff visual misidentification, especially when
you already had the advantage of prior knowlege you didn’t share with
your poor victim… :slight_smile:

Peter Rowe (G.G., 1979)

(and even after 30 years, I can’t say I always get every visual guess
at an ID right. Not even close. One thing that G.G. and those decades
taught me is that you cannot always tell just by eye, what something
is, especially if your torturer… oops, I mean the person asking
you… has picked some small especially unusual and unlikely
material to “test” you with.)


#4

Hi David,

I am a long time lurker and gem dealer in this forum and I think
today I will just give my 2 cents worth…

There is a company in Sri lanka who diffuse White Star sapphire and
"powdery blue", this guy is a nice guy and sells his stones as
treated / Diffused Stones (I also have a in my collection a Fine 11ct
Alexandrite like Quartz) his web site is
http://www.supergreentopaz.slt.lk/order.htm

I think your stone may be one of his stones.

Hope this helps
Ahmed shareek
http://www.finengemsonline.com


#5

Do you / have you tested the RI of your stone? Have you calculated
the specific gravity of your stone? Have you immersed it in oil to
see if there are layers, as in an assembled stone? Have you used
your dichroscope? Have you used a spectroscope/polariscope? etc. In
other words have you had the stone tested / have you tested the
stone? Without proper examination and appropriate data, I would not
hazard to identify your stone.

John


#6
Close examination reveals flaws and fissures breaking the surface,
minor but looking like a natural stone, not perfect like a lab
grown 

There is only one sure way to separate natural star sapphire from
lab grown. It is magnification. Other tests may provide a clue, but
none of them conclusive. If you see flaws breaking the surface, it is
important to identify what kind of flaws. If it like exploded gas
bubbles, it is probably lab grown with diffusion. It also could be
natural sapphire, which was heated in presence of titanium oxide.
Since stone have rough back, do you see and needles from the back
under magnification. There is no easy answer. You need to study gem
internals and understand how it was formed, and if formation is
consistent with what is known about star sapphires.

About your experience with GIA gemologist. I have been a critic of
GIA for years, but with all that, their program is still the best
available. The problem arises because they want everybody go out and
boast their GIA credentials. They misguidedly trying to instill a
sense of confidence in the graduates, when quite the opposite needs
to be done.

The elephant in the room, which everybody ignores is that with all
the training, and all the equipment, mistakes are a real possibility
and the most of all, a gemologist must never offer professional
opinion about any gemstone, without examination, and even after that,
a disclosure of possibility of error, must be made.

Leonid Surpin
www.studioarete.com


#7
If you do not know, keep your mouth shut, you gain more trust by
not knowing than by one wrong answer. 

Amen!!! I am always absolutely honest about stone id’s with my
customers. I tell them exactly what it is, and if I’m not sure I
either say “I don’t know what that one is, but it sure is pretty,
isn’t it?”, or I’ll say “I think that is… but I’m really not
sure. It sure is pretty though, isn’t it?” Most of my customers are
buying something that appeals to them visually, and if I can’t id the
stone they are ok with it. Some care - both about what it is, and
whether it is natural, treated, or synthetic. Each customer is
different, but they ALL want to be told the truth.

Beth Wicker
Three Cats and a Dog Design Studio
http://www.bethwicker.com


#8

David- One of the key identifiers in a natural star sapphire is the
presence of inclusions within the stone, such as fingerprints (healed
fissures), feathers (cracks) and small crystals of other minerals.
With good 10X loupe technique, you should easily be able to see
these, if they are present. Natural inclusions prove the stone to be
natural.

Some of the things you mentioned are good indicators of origin, but
NOT proof. Uneven bottoms, uneven color, “grain” and off center
stars are rarely seen on Linde stars, while a softer star that seems
to originate deep in the stone, not on the surface as in a Linde, are
what we see in natural stars. The difference in overall appearance
between natural stars and lab grown ones is generally pretty obvious.
Quench crackling would be unlikely to change the look of a Linde.

Unless the color is a very pure and vivid blue, natural star
sapphires are usually pretty affordable in price. The quality of the
star, size and color are the main value factors.

Please don’t judge all gemologists by your experience with the lady
gemologist. Like any training program, GIA graduates a wide range of
students, from outstanding to just barely passing. And, as you know,
having a diploma is no substitute for experience-- you have lots of
experience, so I suggest reading a few gemological texts, or even
better, try the GIA correspondence course and join us gemologists–
sounds like you will have a leg up!

Jim Sweaney, CGA, FGA, GG
www.mardonjewelers.com


#9
don't have instant faith in anyone claiming to be a gemologist. I
just had one in my shop, GIA trained in colored stones. I asked
her opinion on what I believed to be a small padparasha I had
bought from a customer cheap. I didn't tell her I had already
tested the refractive index and observed pleichroism with a calcite
dichroscope. She said it might be a tourmaline... really? 

Yeah, David, we had one worse - gemologist said it was precious topaz
($1000+) when it was obviously plain old everyday smoky quartz (25
cents). There’s a world of difference between going to school and
learning tests and being a “rock and gem person”. Finding someone
who’s both is more rare than some might think.


#10

Hi John,

Without proper examination and appropriate data, I would not
hazard to identify your stone. 

Sure you can ID it. It’s a blue star stone. (DG)

Dave


#11
I just had one in my shop, GIA trained in colored stones. I asked
her opinion on what I believed to be a small padparasha I had
bought from a customer cheap. -- 

Not real sure what you had in your shop, if it was a gemologist, or
someone who took a four hour class through GIA in colored stones.
(Sometimes larger department stores will send their associates to
get trained)

Look for hexagonal growth bands that are naturally found in
sapphire. Look for gas bubbles just below the surface, which would
lead to synthetic. You may even need to see what kind of reaction you
get under long and short wave UV.

I’ve looked at several really good synthetics over the last couple
years that were initially thought to be genuine. RI is the same, DR
stones, and stars can be uneven, wavy and look very natural.


#12
don't have instant faith in anyone claiming to be a gemologist. I
just had one in my shop, GIA trained in colored stones. I asked her
opinion on what I believed to be a small padparasha I had bought
from a customer cheap. I didn't tell her I had already tested the
refractive index and observed pleichroism with a calcite
dichroscope. She said it might be a tourmaline... really? 

I’m not sure how accurate someone is obligated to be when asked to
give just an opinion – a free opinion? – absent his/her own testing
equipment and time. Perhaps her reply was a courteous version of “one
can’t be sure w/o full testing, which costs $xyz.”

Lorraine


#13

HI Peter;

I didn’t start this post to inflame all the GIA folks out there, but
I expect some to get a bit defensive of their credentials. As for my
opinion on gemologistts, GIA or otherwise, they’re like jewelers,
some of them know what they’re doing and some don’t.

Let me give you some more on the gemologist I mentioned.
I didn’t set her up to trick her. I showed her the stone, asked her
opinion, and she said, could be a padparasha, maybe it’s a
tourmaline. I didn’t carry on the conversation after that. Maybe she
was just blowing me off. But I’ve got dozens of tourmalines, in
dozens of colors, reds, greens, blues, bi-colors, even a silvery
gray one. But even casual observation would, I think, tell you that a
sapphire has an observably harder and brighter light, and I’ve yet
to see a tourmaline exhibit obvious pleichroism. I expected her to
take a better look before she just threw out an opinion like that. I
showed it to another gemologist and gem cutter and he said, short of
more testing, he was pretty sure it was a natural. This guy is one
of the more knowledgeable gemologists I’ve known, also a buyer of
rough and a cutter. I’ve also seen my share of real padparashas and
lab grown ones and I’ve yet to see a lab grown that looked like a
convincing padparasha. This one is an older stone, taken out of a
mounting that I’m pretty sure was made before the labs started
producing padparasha look-alikes or using diffusion.

Gem identification, with the limited equipment I have is largely a
process of deductive reasoning. And I don’t claim to give a
professional opinion. If it has this, it’s might be that, but if it
doesn’t have this also, then it’s probably that, etc. The right or
wrong RI, evidence or not of characteristics of lab grown methods
like curving lines, maybe some microscopic rain, some zoning,
included crystals of other minerals, etc., makes me believe it’s
likely natural or man made, etc. I’ve worked with gemologists who had
amazing arcane knowledge of gems and some who were prone to pulling
it out of a bodily orifice. All that said, I think the odds of a GIA
trained gemologist knowing their stuff is probably better than a self
proclaimed jeweler actually being good at their job. I’d be just as
skeptical of the JA certification. I know one local JA certified
master bench jeweler who I don’t know how passed the tests, and a
another local guy with a sign saying “Master Jeweler” who I wouldn’t
hire to sweep my floors.

As to the denim blue sapphire question, my friend called today, said
he had his gemologist friend take a better look at the stone in
question and he has reversed his opinion and believes it’s a genuine
stone, albeit diffusion treated. Like I said, I’m no gemologist, but
four decades of buying and setting stones has trained my eye a bit.
What I was asking in my first post was if anyone else has heard of
these stones and that they were being made from doctoring lab grown
star corundum. I’d never heard of it, hence my original doubts. I
paid around $150 for it 8 years ago, it’s around 6 carats, cheap but
then I don’t expect diffusion treated stones to cost much. It’s worth
a little more that whatever it looked like before it was treated, in
my opinion, which was probably something unsaleable, more or less.
I’ve got one very pretty diffusion treated orange sapphire, around
$80 per carat which looks very much like a Mandarin garnet in color,
not as bright (RI again) but no dichroism that you can see with the
naked eye. The padparasha I have that I’m convinced now is natural
has an obvious color shift, to my eye, at least.

David L. Huffman


#14
I didn't start this post to inflame all the GIA folks out there,
but I expect some to get a bit defensive of their credentials. As
for my opinion on gemologistts, GIA or otherwise, they're like
jewelers, some of them know what they're doing and some don't. 

I think it’s important to understand what a gemologist is, for
David’s thread. A gemologist is not (necessarily) a stone/gem expert.
A gemologist is a stone TESTING expert by training. Supposedly a
gemologist is supposed to know how to tell synthetic from natural,
ruby from spinel, and all sorts of things like that. They don’t
necessarily know what quality is about, or a good stone from a bad
one, and many can’t tell a paddy from a tourmaline by sight. That, as
both David and Peter have pointed out, takes plain old experience,
and doesn’t even require a GG to learn. Gemologists perform an
important service in the industry - I think it’s important to
acknowlege that, for better or worse. But I know more about rocks and
gems on a level of perception than many that I’ve known, just from
being in the business and growing up with rocks all my life. Not
stuff you learn in a classroom. Myself, I started on the path to GG,
and realized I didn’t like it much and I could just pay somebody to
do those things, as needed. A love of gems doesn’t require a
refractometer…


#15
...New grads have lots of raw knowledge crammed into their heads,
but may need at least a few years of letting it cook in there, ie
experience, before their real grasp of the has matured. 

And let’s not forget to stir the pot once in awhile. Without that, a
lot of sediment settles to the bottom and is often burned. I.e.
lost. LOL Are certified gemologists required to do Continuing Ed to
remain certified? I would hope so as new treatments for gems are
discovered and need to be noticed.

Michele


#16

Dear David,

tourmaline has very strong pleochroism, one of the characteristics of
the mineral. Sapphire’s pleochroism is less noticable as its
birefringence is much lower than most minerals. However, I wouldnt
expect to see a star tourmaline-cats eye, yes so seeing a star is a
great guide to what you have with regard to mineral type. Lab grown
cat’s eye and star stones have been around since the 1960’s and some
of the diffusion treatments have been used on sapphires in particulr
since the early 70’s so something bought secondhand 8 years ago may
very well be treated by a range of techniques which have become more
widely known recently but were used to deceive when they were done. I
have a ruby that is Victorian in age and contains a number of
characteristic flaws. 2 professionl gemnologists have looked at it
and both are convinced it is a doublet, 1 saying it has a glass
backing, the other saying it is garnet. With a mounted stone either
of them could be right, or it may be a solid, the tested
characteristics merely eliminate most other possibilities and then
one has to rely upon experience to make an opinion.

I also own a blue spinel which came from Jos, in Nigeria. According
to normal gemnological reasoning, it isnt natural but I know very
well it is. Star garnets are another one that shouldnt be but they
are not uncommon. Occasionally the earth throws up an oddity that
makes us have to think again about what we know or think we know and
that is where most professionals quote an opinion rather than an
absolute fact.

Nick Royall (not a gemmologist but previously a gelogical analyst)


#17
However, I wouldnt expect to see a star tourmaline-cats eye, yes so
seeing a star is a great guide to what you have with regard to
mineral type. 

While they don’t look much like sapphire, I have a couple small
tourmaline cat’s eyes, and have seen a few stars as well. Unusual,
and not at all as clear as those in star sapphire. But I’ve seen a
few, so don’t rule it out entirely. star stones can surprise you
when you don’t think they should be there. Star garnet, for example,
or even cat’s eye or star opal (!)… I’d agree that a good star, and
it’s appearance, can be a good guide, and greatly reduces possible
identities, but I’d not use it to totally rule out materials other
than sapphire.

Peter Rowe


#18
...New grads have lots of raw knowledge crammed into their heads,
but may need at least a few years of letting it cook in there, ie
experience, before their real grasp of the has
matured. 
And let's not forget to stir the pot once in awhile. Without that,
a lot of sediment settles to the bottom and is often burned. I.e.
lost. LOL Are certified gemologists required to do Continuing Ed
to remain certified? I would hope so as new treatments for gems are
discovered and need to be noticed. 

Certified? Just what certification are you talking about? A diploma
from GIA or anyone else is just that. A diploma, which verifies that
the owner has recieved certain training and passed some exams.
Certification would mean some organization is promising continuing
complience and competence, and possible adherence to certain
standards or practices. While some states require some licensing of
appraisers, which can amount to the same as certification, I know of
no such requirement for gemologists, at least not in the U.S.

Peter Rowe G.G.


#19
A gemologist is not (necessarily) a stone/gem expert. A gemologist
is a stone TESTING expert by training. Supposedly a gemologist is
supposed to know how to tell synthetic from natural, ruby from
spinel, and all sorts of things like that. They don't necessarily
know what quality is about, or a good stone from a bad one, 

John, I have to disagree with you here. Gemological training for a
gemologist or graduate gemologist diploma includes more than gem
testing. For one thing, you have to know the possible options for a
gems identity if you are going to be able to interpret test results,
so a good familiarity with all the types of gems is included and
important. And, the course sequences include courses specifically in
quality grading, both in diamonds and colored stones. So training in
determining good from bad quality gems is most certainly very much a
part of that training.

It’s pretty easy to understand what the training covers. If there is
an aspect to gems that is directly useful to someone buying or
selling or representing gems in the jewelry industry, either
wholesale or retail, but especially in retail stores, then it’s
likely a part of the gemological training programs. This means the
ability to understand and explain to customers or bosses, all the
various different gems, their properties, advantages, disadvantages,
varieties, etc, as well as relative values of each and why. You can’t
competently sell gems without some level of these understandings, so
it makes sense that the training covers these things as best it can.
You add the ability to recognize, test, determine, etc, the actual
identities in order to be sure you’re correctly representing stones
as what they really are, or correctly identifying stones belonging
to someone else in order to discuss them accurately.

For the most part, the training concerns dealing with cut gems.
There is, of course, some overlap into rough gems since the basic
understandings of the gem material that let you identify and quality
grade gems requires understandings that extend to rough stones too.
But the training does not delve any deeper into the mining or
mineralogy than is needed to let you discuss the gems with some depth
of knowlege, especially with the public. And although the training
teaches you to use and understand what aspects of gems are used to
grade quality, value, usability of gems, it is not the same as years
of experience with actual exposure to gems over time. This can be
learned only by that actual exposure to gems over time. The courses
show you as much as they can, including a wide variety of gems and a
whole lot of concentrated but there are still limits,
and a newly trained person in ANY field, from medicine to
engineering to gemology, will still get better and more knowlegeable
with experience and time.

Of course, the training in identification is an area the normal
trade, buying and selling, of gems, would not teach you, so it’s
especially useful as an addition to the conventional wisdom that
experience will give you. Quality grading, on the other hand, is the
reverse. Experienced gem dealers and lovers will be able, by eye or
with a loupe if they like, to come to exquisitly detailed opinions
of gem value and quality, just based on that experience. The training
on gem grading included in gemological training is both to give the
newcomer a head start on learning this stuff, so that they’ll reach
that level of experience and competence more quickly, that time will
already produce.

And importantly, it adds a method of consistent communication, so
that everyone is speaking the same language in describing gem
quality. This is NOT something the traditional non-gemological
approach gives. Nothing is perfect, of course, and the experienced
gem lovers will often find that standard nomenclature is not totally
adequate to distinguish fine levels of difference in quality, but
it’s a starting point that’s better than what we had before. And
training in this grading nomenclature and system is perhaps better
than learning it on your own, because some of the distinctions and
grades are very precisely defined. Many of use have had experience
with people claiming certain clarity or color or quality grades of
diamonds and gems, which end up being not quite so accurate. Often,
it’s because these are people who’ve NOT been accuratly trained in
these systems and their use, but who’ve picked it up on their own,
thinking they now understand it, but who don’t realize that they’re
not quite there. Examples are gem dealers who claim the GIA diamond
graders are too harsh, assigning too low a grade to a given stone.
This is a bit like a fisherman saying the ruler is wrong, that his
trout is actually a few inches longer than his ruler says. If GIA
defined the ruler and the grading terms, they’re best able to teach
people to use it accuratly. Other systems exist and are just as
valid, so long as they don’t claim to be the same grading system even
when different standards and definitions are used. This is one aspect
where non gemologists seem to make more errors than those with the
formal training.

But of course, you’re totally correct that anyone can learn any of
this without any formal training at all. It’s all
published, and not exceptionally complex as to require intense
teaching to comprehend, so someone who wants to learn it on their own
in the library and gem shops, etc, can certainly do it, and some
aspects of such education will exceed what any course can teach.

You’re certainly right that a love of gems doesn’t require a
refractometer, or even a loupe. But fully understanding what a
refractometer is measuring, and why, will give your experienced eye
an edge to understanding what you’re seeing, and why it’s worth
looking for or at. The instrument gives you absolute repeatable
numbers that have their own use. The eye doesn’t give you the
numbers, but it’s just as perceptive, and maybe more so, able to
integrate many aspects of a gems appearance and appeal into a sum
total opinion. But in a world where, for example, prices of diamonds
often depend on the stated grades, the gemologist who knows exactly
what a given grade is supposed to define, and can assign grades
accuratly in accordance with those definitions, will be at an
advantage over someone who’s trained themselves over the years, and
may think they know better.

Cheers
Peter Rowe


#20

Hi Nick;

Yes, I forgot about the cat’s eye gems, think I remember seeing a
cat’s eye tourmaline once. Cat’s eye chrysoberyl, yes, not unusual. I
knew the synthetic star corundum has been around for a while, but I
thought I remember the beryllium treated orange sapphires hitting the
market just a few years ago. At first the treatment was shallow, then
they found a way to drive it deep into the stones. But back in the
80’s, it seemed things like tanzanite and padparasha weren’t out of
reach, pricewise. We had big, nice stones. And who would have thought
the orange garnets would get so expensive. Nobody had heard of
demantoid either. Garnets and tourmalines, amazing color range. I’ve
got a 1 carat neon-blue Paraiba that I bought for something under
$200 years ago which I’m betting would cost a couple thousand now.

I remember having a blue sapphire that took me an half hour with a
microscope to determine it was a synthetic, very clever fake, but
one type of inclusion you just don’t seen in a natural. When you see
things offered at unusually low prices, you have to take a close
look. There was an article in one of the trade rags about blue spinel
a while back and I’ve wanted to get my hands on one since. The stuff
that worries me mostly is the quartz hitting the market these days in
the form of amethyst and citrine. Huge stones, dirt cheap, these have
to be grown, there’s no way they’d sell them so cheaply. But as far
as I know, the average GG isn’t likely to have the equipment to see
twinning, unless you know of a trick. I’ve got a student from Russia
with a ton of the stuff and she’s hot to make up and sell stuff with
it. I’m afraid I’ve got her a little worried about it, the color is
fantastic, absolutely clean, and the cutting rather sloppy, and they
were cheap. Had a customer send me an email of a big citrine on ebay,
way too cheap to be the real thing, unless I don’t know of some huge
source that’s been uncovered. I told her I doubted it was genuine,
she could buy it if that didn’t make any difference to her, but I
could meet the price and it would take me a while to dig up one that
big. I’ll set whatever they want, I just don’t buy it myself unless I
can represent it truthfully and accurately.

David