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Odd effect on surface of stones


#1

Hi all,

I’ve seen an odd pattern on the surface of stones in various gem
stores and stalls.

I’m wondering if its a tell tale sign of a synthetic.

The best way I can describe it is a wavy film with a sheen similar
to oil on water on the facets of the stones viewable only at certain
angles. Is it a by-product of treatment? A synthetic?

Am I being paranoid?

Any explanations welcomed.

Karl.


#2

I’ve seen that too. In most cases it’s a fingerprint and disappears
if wiped with acetone.

Which leads to a story. A few years ago I dropped in to visit and
drink coffee one evening with my gemology prof. He pulled out a
stone. “Here, tell me what you think this is.” I held it under the
living room lamp, turned it this way & that & in the process saw the
selfsame faint curved lines. I said, “I think it’s a Verneuil
synthetic ruby or Verneuil alexandrite simulant, anyway I think it’s
a flame fusion stone because I think I see curved growth lines.” He
was nonplussed; I had hit the jackpot, it was indeed a Verneuil
synthetic. Only after having noted the same pattern on numerous
other stones did it dawn on me that what I had seen was a
fingerprint.

Cheers,
Hans Durstling
Moncton, Canada


#3

Or maybe the stones are oiled…?

teri
An American Cameo Artist
www.cameoartist.com


#4
I'm wondering if its a tell tale sign of a synthetic.
The best way I can describe it is a wavy film with a sheen similar
to oil on water 

I’m pretty sure what you’re seeing is the sheen of oil on…
polished stone (synthetic or otherwise). Sadly, there is no simple,
easy way to identify a synthetic.

–Noel


#5

Oil on gemstones is part of the cutting process and would not remain
on the gemstone past its being set in a mounting. The only gemstone
that has “oil” as a treatment would be emeralds. (which is a misnomer
as there is no actual oil in the products used to “treat” emeralds)
And then the treatment is used to fill fractures inside a natural
gemstone and not enhance the surface.

Synthetic stones, which are lab grown would hopefully not have
natural fractures that would need to be treated. Perhaps Mr. Chaundy
is seeing some of the coated and / or diffusion treated topaz that
is on the market. It’s very cheap, natural, white topaz and has a
tendency to look like oil on water, since the coating or diffusion
is done after the gemstone has been faceted.

And, there is an easy way to tell if a gemstone is synthetic… ask
a G.G. (graduate gemologist)

Nanz Aalund


#6

I am not an expert on stones, but I have noticed this sheen on the
surface of sunstones for sale. My suspicion is that it has something
to do with the alignment of the cleavage planes in the stone…perhaps
making the “best” use of the size of the rough at the risk of future
partings parallel to the iridescent face. Am I way off line?

Rose Alene McArthur


#7
which is a misnomer as there is no actual oil in the products used
to "treat" emeralds

Actually a number of actual oils have been and are used to treat
emeralds, often in combination with light heating and pressure. A
large percentage of emeralds are now treated with other types of
fracture fillings that do not use oil but oil has always been, and
probably will always be, the treatment of choice for emerald. No
machine oil will not do it, but there are a number of other oils
that work quite well.

Daniel R. Spirer, G.G.
Daniel R. Spirer Jewelers, LLC
1780 Massachusetts Ave.
Cambridge, MA 02140
@Daniel_R_Spirer
www.spirerjewelers.com


#8

Thanks to all who have contributed to this thread.

The effect is not from a fingerprint - the lines are too far apart.
Think of the way height of hills on an ordenance survey map are
shown.

The effect is visible to the naked eye from a foot away.

I’ve noticed it on both ‘corundum’ and ‘peridot’ of fairly deep
colour.

It may be Topaz then as Mr. Aalund suggests. I am reluctant, though,
to spend money on such a stone and show it to a gemologist just to
find out if it is a synthetic or not.


#9
It may be Topaz then as Mr. Aalund suggests. I am reluctant,
though, to spend money on such a stone and show it to a gemologist
just to find out if it is a synthetic or not. 

I am a Ms not a Mr. ;~} Do you not have a friend who is a G.G. who
could go walking the stalls and craft markets with you? If you don’t
look at the Rio Grande, Gems and Findings catalogue to see samples
of the gemstones I discussed.

Most of the trouble I read about posted on Orchid stems from the
isolated view too many metalsmiths have of our craft.

All this concern about being cheated and not knowing on
gemstones could easily be solved by taking a GIA (Gemological
Institute of America) class and then joining a GIA alumni assoc. in
your area. I don’t want to sound like an advertisement but I use my
GIA training everyday, either when I am buying or when a friend or
client needs advise.

Education is never a waste especially when it is about a topic so
close to metalsmithing and jewelry.

Nanz Aalund


#10
Education is never a waste especially when it is about a topic so
close to metalsmithing and jewelry. 

I’ll second that view. It never fails to amaze or dismay me, the
percentage of people in the jewelry field who make their living
selling diamonds and colored gems set in precious metals, who’s main
expertise is marketing. Many on this list are quite knowlegeable
about what they do in metals, but all too limited in their full
understanding of the gems they put into the metal. If aircraft
maintenance mechanics also learned most of what they know from
hearsay, conversations with other equally untrained folks, and the
rumor mill, we’d have a lot more plane crashes. This list is a better
source of info perhaps, for many people than is simply asking the
other jeweler in the next stall at the show who also doesn’t really
know, but there can be so much at stake in terms of finances,
responsibility to your own reputation and professionalism, and the
like, that it’s always seemed to me incomprehensible how many
jewelers and craftspeople simply don’t bother to actually get some
proper training. My own employer is a fine example. Three generations
of jewelry making in the family, since the 30s. The two brothers who
run the thing now bought it, and learned it, from their dad. We’ve
got a bunch of employees. But I’m the only one who’s ever taken any
sort of gemological training course (I’m a G.G.), and they hardly
ever even ask me to help with it. Listening to them sell a diamond
has on more than one occasion made me wince, and the stuff I hear
them say about colored stones is even more often not quite right.
That’s the result of learning a deep understanding of colored stones
and diamonds by reading the mags and listening to vendors, but not
following through. You get most of it right, only to stumble badly
on the details. And the thing is, people with this sort of spotty
education often have no clue what they’re missing. They’re sure they
really know their stuff. This often includes gem dealers from whom
many of these jewelers seem to have learned this junk.

The bottom line, folks. Get a proper education on gems, metals, and
jewelry. GIA is one very good way to do it. It’s not the only way.
But hearsay and hoping you’ll “pick it up somewhare”, are not good
ways. Take the GIA classes. The cost can be easily spread out over
time. They can be taken as correspondence courses at home, often with
even better results and much lower cost than taking the class room
classes at their campus. Just do it. You’ll never regret the
decision to do so.

Peter Rowe


#11
I am a Ms not a Mr. ;~} Do you not have a friend who is a G.G. who
could go walking the stalls and craft markets with you? If you
don't look at the Rio Grande, Gems and Findings catalogue to see
samples of the gemstones I discussed.

Oops. My apologies Ms. Aalund.

I’d love to take the GG course. I just need to save up enough :wink:
For now, Matlins, Hughes and newman are my paperback tutors.

It’s more out of curiosity and to see if anyone else has noticed it

  • it may be that I’ve taken another step toward madness!

I agree that knowledge of gems are important. With a majority of
stones on the market being treated in one way or another and a few
sellers being less than honest about their treatments there is a
danger of selling a piece with a stone which you believed was one
thing only to have the customer return with it after having it
tested telling you its something else.

There goes your reputation. If I’m really unsure about a gem I don’t
buy it. Another alternative is to take it to a gemologist before I
set it (if the stone is a must have).

Regards,
Karl.