large emerald in it. ...used some of the heat shield type
stuff.. Anyhow, the emerald, while not cracked or damaged in that
respect, changed color to a dark ugly sort of olive green. ...does
anyone know whether or not the original color can be restored?..if
so, how?
Since I get the Digest version, maybe some one else has already
responded to this query. I know Randy Smith did as he sent me a copy.
Firstly, your jeweler friend committed one of the “sins” of jewelers.
Probably 99.5% of all Emeralds are “oiled” (of course there are some
pure crystal Emeralds around that don’t need oiling - but mere
mortals like us rarely get to see them - for example, of the 300+
carats of faceted Emeralds that I had at the recent Tucson Show -
only 5 stones weighing a total of 5.02 carats fell into this category
and were selling at $2500 - $ 3000/carat wholesale).
The “oiling” of Emeralds is done to fill in the fractures and
inclusions with a material that has a Refractive Index close to that
of Emeralds and to make the defects seem less apparent. Up until
recently the industry required that the “oiling” process be
completely reversible. This means that the “oiling” is not permanent
and periodically has to be replaced. Common “oiling” materials
include (or have included in the past) Mineral oil, Palm Oil, Cedar
Wood Oil, Opticon Resin without hardener, Paraffin, and a whole range
of others. Some more permanent treatments include Opticon Resin with
hardener and UV cured photopolymers.
In order to safeguard this “oiling,” jewelers must not subject the
stones to heat, flame, steamers or put them into ultrasonic cleaners.
Also the unset stones should not be stored in stone papers or on
cotton as this will eventually pull out the “oiling” from the stones.
I was taken to a Bank Vault of a customer to see his very fine stones
(which he assured me were of much better quality than mine) and which
had been stored for a long period in stone papers in the temperature
and humidity controlled environment of the Bank. Needless to say the
“oiling” had pretty much gone out of the stones and they were quite
unattractive when he showed them to me.
By applying heat to the large Emerald stone, and depending upon what
heat shield material was applied, the minimum your jeweler friend did
was to make the “oiling” much more fluid and allow it to run out of
the Emerald and be soaked up by the heat shield material. Depending
upon the amount of heat applied, that is all that happened and the
“oiling” material can be removed and the oiling re done.
One basic problem is to determine exactly what material was utilized
for the initial “oiling” in order to utilize the correct solvent to
remove the original “oiling.”
Since you mention that it is a large Emerald, and may be a quite
valuable one, it might be interesting to have the Emerald treated by
a professional company specialized in removing and re-treating
Emeralds.
One that comes to mind is the Arthur Groom Company in NYC that
advertises having developed a treatment for Emeralds that is
permanent and at the same time reversible. Apparently they can
discover what material was used in the original “oiling,” remove all
vestiges of the original material, treat the Emerald with their
“secret” formula and their treatment does not have to be periodically
repeated. The fact that their treatment is reversible means that in
the future a buyer can have the treatment removed from the stone,
examine the emerald in its natural state and have a certification
issued and then re-treat it. (I have no connection to this company)
“Gemtrat” address is Arthur Groom & Co. Ph (212) 832-9100. E-mail
AGGMTRTS@sprynet.com. As per Mark Liccini, in his article on Emerald
Enhancements, Color & Light magazine, (International Gem Society) Vol.
1, Nr 2.
Here’s a quote from another e-mail list from the recognized authority
on Emeralds (and author) Fred Ward.
"Regarding emeralds and the chemical brews that are used to mask
inclusions, there are few long-lasting or permanent fillers. Arthur
Groom’s trademarked “Gematrat” treatment is guaranteed by Groom to be
permanent and if it ever fails he will replace it free “forever.” I
consider a hardened polymer to be permanent or almost permanent. That
doesn’t mean just swiping a little hardener over the filled fracture
but mixing hardener with the polymer. These may turn cloudy over time
or suffer other defects, but they last longer than the usual fillers
that evaporate and/or deteriorate in time. Unhardened polymers, such
as Opticon without the hardener, last only a few years. Oils, natural
or synthetic, are also short-lived.
Best regards Robert Lowe Lowe Associates - Brasil Gemstones, Rough,
Specimens Tucson, February 7 - 12, 2002 - GJX # 205 e-mail
<@Robert>
** Hanuman’s Response **
Back in 1997 Ganoksin has published the Fred Ward’s Case “The Emerald
Case Line”
http://www.ganoksin.com/borisat/nenam/emerald-case.htm
We also published the Gemlab Report about Emerald Oiling (In-Fill)
Process
http://www.ganoksin.com/orchid/archive/9710/msg00280.htm
Hope you will find these article informative
Your host
Hanuman