Hello Orchid,
The following is the first issue our newest Monthly
E-letter; The GemLab Report. Written by Ted Themelis from GemLab
We Hope that you will find it to be a useful service.
Dr. E. Aspler
GEMLAB REPORT:
by: Ted Themelis
themelis@mail.otenet.gr
In This Edition:
- About The Author
- CZ & their Variations
- The truth about oWhite sapphiresoe
- About the so-called oDouros rubiesoe
// – About The Author --//
Ted Themelis received his Bachelor of Science degree from the
City University of New York in 1975. He has worked extensively
in development, engineering, and manufacturing of innovative
gemological testing instruments and apparatuses. Since 1979, he
has been involved in various gemstone enhancement experimental
projects, mostly in the heat treatment of ruby and sapphire. He
has traveled extensively to the most inaccessible gem mining
areas in Burma, Sri Lanka, Thailand, Vietnam, Pakistan, India,
Nepal, Tanzania, Kenya, S. Africa, Venezuela, Colombia, Brazil,
and elsewhere. From 1984-1986, he served as the Director of
Research & Development of the Accredited Gemologists Association
in the USA. He has published over 120 articles in the field of
gemology, on the subjects of identification, treatments,
inclusion characteristics, among others. He is the author of oThe
Heat Treatment of Ruby and Sapphireoe, the only book that deals
exclusively with the subject. In 1995 he fabricated the first
electric resistance 1800oC furnace in the market, using MoSi2
1900oC heating elements with full atmospheric control,
specifically designed for the heat-treamtent of ruby and
sapphire. He maintains state-of-the-art gemstone enhancement
laboratories in Europe and in the USA, providing heat treatment
technology, equipment, and services to the industry.
// – CZ & their Variations --//
In the early 1980AEs when cubic zirconia (ZrO2), commonly known
as CZs first debuted in the 47th Street as odiamond substitutesoe,
or odiamond imitationsoe, many jewelers were taken to the
cleaners. For over 15 years, CZs have their own lines of jewelry,
proudly presented, advertised and sold in the open market. In the
last couple of years, CZ manufacturers present their newest
products (derived from the original CZ recipes), which are
basically CZ with distorted physical and chemical properties.
This is due to manufacturersAE changing parameters that may differ
among processing batches (runs). Although stabilization of the
cubic zirconia is the crucial part of the chosen process, it is
possible for the crystal-grower a) to change dosodology of the
basic ingredients b) to change process and processing parameters
c) to use different stabilizers, such as yttrium oxide, calcium
oxide, etc. d) to add various chromophore impurities compatible
to the mix. This will result to slight variation of the physical
and chemical properties of the final product, as well as a
variety of colors may be produced (yellow, green, red, etc.).
On colorless CZAEs, under carefully controlled conditions, the
various chromophore impurities may produce slight tinge of color,
thus altering their opure colorlessoe state. The overall
appearance of these CZAEs are reasonably comparable to the various
diamond colors (D, E.F, etc.), but never exact. Thus, these CZ
may be suitable to be used as oapproximate mastersoe for diamond
color grading. The CZ are available in the market under various
names: Diamon-Z, Diamond-QU, Diamonair II, Diconia, Diamonique
III,Diamonite, Fianite, Phyanite, Shelby, Zircomium Yttium oxide
and many others.
// – The truth about oWhite sapphiresoe --//
About six years ago, a sudden and huge supply of white sapphires
mostly in melee sizes hit the international market in a big way.
On specific jewelry lines were CZ were used as melee stones, they
were replaced by these white sapphires, so these jewelry
manufacturers can claim that the final product consisted from
100% natural stones. Knowledgeable gem dealers and gemologists
alike, know that truly white sapphires (called oleuco-sapphiresoe
, from the Greek leukos=white, sappheiros=sapphire) are quite
rare in nature, and almost never encountered in the gem and
jewelry trade. So, where is this onew mineoe as the Thai dealers
advertise in their sales speech? Here is what happened: For many
years, many Sri-Lankan and Thai gem dealers have accumulated
large supply of unsuccessfully heat treated corundums, yellowish,
whitish, grayish and similarly appearing colors. These corundums
had very little or no market value and were condemned as
worthless. However, when these corundums were heated at high
temperature in an oxidizing atmosphere they turned white in
color, with increased transparency and luster. When these
multi-heated nearly colorless sapphires are carefully observed
under proper lighting conditions, their color may be termed as
ooff-whiteoe. There is always a yellowish or grayish tinge when
observed parallel to their table. In conclusion, the so-called
onatural white sapphiresoe in reality are multi-heat-treated
corundums, derived from unsuccessfully previously heated
corundums.
// – About the so-called oDouros rubiesoe --//
There are many synthetic rubies set as melees in jewelry. Take
for instance the so-called oDouros rubiesoe. These rubies were
introduced early 1993 and were grown using flux method, probably
by spontaneous nucleation. These rubies were never advertised and
marketed openly. Checking with the SSEF gemological laboratory in
Switzerland, only one or two Douros rubies were detected since
1993; checking with the AIGS laboratory in Bangkok perhaps one
Douros ruby was detected. I have seen the entire production
consisting of over 12,000 carats. Where all these stones went? In
my opinion, most of these rubies are set in jewelry, as melee.
How can you detect these rubies, created by spontaneous
nucleation, without visible flux-inclusions and so small in size?
It is very difficult. Who has the time to check all these melees?
The bottom line is that these synthetic rubies are beautiful, the
jewelry are sparkling, and the price is right (sometimes a
bargain). Warning: These synthetic rubies (specially
oDouros-rubiesoe), are frequently encountered set in upper-end
jewelry emanated from Thailand.
Any Comments should be posted to service@ganoksin.com or directly to
the author at: themelis@mail.otenet.gr