Diamond, gemstones, precious stones

The odds on finding an uncut diamond, unless one happens to be walking on a
patrolled, electrified, mined and guard dog guarded beach in South Africa,
are fairly rare. However, uncut diamonds have a number of characteristics that lend ease to their identification.
They normally appear as cloudy, white or slightly colored pebbles with a
unique coal, greasy feel to the touch as they are excellent conductors of heat. Natural diamonds can be dipped in water and will not remain “wet”. The water does not stick to the surface. These diamonds do, however, stick to common axle grease when passed over them, but most stones will not.
Natural diamonds also occur as crystals and normally have at least one side of the crystal that is flat and appears as a facet. Sometimes more than one side will take on this characteristic.
Positive identification of diamonds or other gems is achieved by a number of
more scientific methods. Specific gravity is a good place to start. This concept is very simple. It is based upon the weight of a certain material in relation to the weight in an equal volume of water.
If the material has a specific gravity of four, it will weigh four times as much as with that much water. Specific gravity is usually checked by using
weighing scales that allow suspension of the specimen. First it’s weighed in
air, then it’s weighed in water. The weight in water subtracted from the
weight in air with the quotient divided into the weight in air. This gives
the specific gravity of the material.
Most gem materials have a specific gravity of less than four. If somebody
wants an accurate but fairly fast method, he can produce a few heavy liquids
and bottle them to suit his needs. There are a number of liquids such as
tetrabromo ethane and methylene iodine that will work. The first having a
specific rate of 2.95 that can be diluted with kerosene to any gravity one
wishes and the second, 3.33. It can be diluted with toluene to produce a
series of liquids of certain gravities in between. Leaving the material in
question in the bottle, you can tell at a glance if correct and what the
specific gravity and the density is.
The specific gravity of diamonds varies slightly depending on where the
diamond came from but will fall between 3.50 and 3.53.
The next reliable indicator used is a scale of hardness indicator. As most
people realize, diamonds are the hardest stone in the world. The hardness
scale normally refers to something called Mohs hardness.
The Mohs scale is a 0 – 10 scale. There is another scale that’s 0 -15 making
it easier to differentiate between the marginal gems that fall between 9 – 10, but the Mohs scale is primarily in use.
Hardness simply refers to the ability of one material to scratch another.
Harder material always scratches a softer material.
The difficulty in making the scratch or appearance does not come into play.
Simply the fact that it can be made.
It should be pointed out that the Mohs scale does not correlate to the
relative hardness of the materials. In other words, a diamond is not something
that is 10x harder than something that is a 1 on the scale. The scale is
simply there to present a basis on which, when a material is scratched,
another material can be identified as harder.
Diamonds are a 10 on the hardness scale. Quartz is a 7 on the hardness scale
as are most types of tourmaline. Most garnets are 7 1/4 on the scale.
Synthetic emerald tends to be 7 1/4 to 7 1/2. Silicon carbide is a 9 1/4 to 9
1/2 on the scale, meaning it will not scratch diamond and diamond will scratch
it.
Opals begin at 4 1/2 and go up through 5 on the scale while turquoise is 5.
Rubies are 9 on the hardness scale.
It is also possible to set a piece of gem material between two Polaroid plates
that are set so that no light may be seen between them. The lower plate that
the gem sits on is known as a polarizer. The upper plate is the analyzer. The
polarizer is fixed but the analyzer is rotated.
If during a complete rotation, the material remains dark with no change, it is
called isotropic. If it is nonisotropic, it will change from light to dark
four times during a complete rotation. The normal nonisotropic pattern is a
sharp cutoff from light to dark, much as extinguishing a fire. By doing this
with a gem, it is possible to establish a refractive index.
However, this is a fairly mind boggling exercise and there are easier ways to
tell, at least with diamonds.
All precious stones have bad name counterparts, some of which are better than
others. Synthetic stones (or by the correct name “created gems”) are defined
by law as “chemically, physically and optically” the same as real gemstones.
They are more expensive than imitation or faux stones which don’t have the
real characteristics but they’re considerably cheaper than natural stones of
the same variety. As long ago as in Victorian times, the French were creating
synthetic rubies, emeralds and sapphires, which is a surprise to some people
who buy estate jewelry thinking it contains a real stone only to find it is a
synthetic stone.
Today’s methods are definitely more sophisticated and create gems so good that
only trained jewelers and gemologists can tell them apart from their natural
cousins… IF THEN!
It’s possible to create flaws in a created stone although it’s more common to see created stones being too flawless or too perfect to be true.
Manmade diamonds have existed for years although they have primarily been of
industrial quality. Scientists have claimed it is impossible to make gem quality diamonds. This is not true. About 25 years ago General Electric
discovered it could make perfect, flawless gem quality diamonds which were impossible to tell from their natural cousins. They decided not to continue
the experiment in any mass version because it was “economically unfeasible.”
In the 1950′s the Soviets discovered a large diamond pipe in Siberia and began
producing gem quality diamonds. In 1962 the CSP decided to buy all uncut
diamonds produced by the Soviet Union as to allow them to be under De Beers
price control. They expected that, based on comparisons with their own mines
in South Africa, the Soviets would begin to run out of diamonds in about 1970
and, therfore, they could afford to buy all the diamonds they would produce.
Approximately once a month, a chartered aircraft lands in London and $50,000,000 worth of diamonds are turned over to De Beers Diamond Trading Company for the equivalent hard currency.
De Beers is not very fond of this arrangement but they feel they must do it
in order to keep up the diamond prices.
However, an unusual development occurred to the shock of the De Beers. The
size of the Soviet shipments did not stop in 1970 but rather increased
dramatically between 1970 and 1975, besides which the diamonds seemed to be
very homogenous in character, averaging 1/4 carat, flawless with sharp, angular edges and a slight green tint. The Soviet diamonds seemed to be remarkably uniform in size and shape and, unlike their African counterparts, did not come in a multitude of round, square, flat, triangular or twisted shapes but rather ere octahedons.
Coincidentally, the Soviets, under some pressure, have admitted they, with a group of 1200 researchers, developed a way to manufacture a flawless gem quality diamond. This process was officially developed in the 1960′s by one Leonoid Veres Yagin. The Soviets claim they are not manufacturing these gems
but they are natural gems that they keep selling to De Beers.
American agencies, after numerous requests, were finally allowed to visit the Siberian mine and found it hopelessly inadequate in size and facilities to process even more than a fraction of the diamonds the Soviets are showing the
De Beers. The De Beers insist these diamonds are natural and deny the Soviets have the capability to flood the diamond market with a virtually unlimited supply…
Besides these man made natural diamonds, there is the problem of cubic zirconia or CZ. It is usually sold under a trade name such as Zirconia,
Phyanite and Diamonique. Technically, CZ is not a synthetic diamond but it is a crystallization of the chemical zirconia that, when cut, has most of the optical characteristics of a diamond.
CZ is not as hard as a diamond and it does have a different specific gravity.
It takes 1.70 carat CZ to equal 1 carat diamond in weight.
CZs, however, in the last few years, have become increasingly close to diamonds and good CZs are impossible to tell from diamonds by the eye. In fact, we had several gemologists look at unmounted CZ and unmounted diamonds,
and they admitted they could not tell the difference. The only one who did pick out the CZ with some regularity was because, he said, the stones were too flawless to be diamonds…
Hardly a reliable way to judge stones.
As one can see, the potential for fraudulent misuse of CZ is quite high and there have been a number of occasions where people were sold CZ instead of diamonds, turned their diamond rings into unscrupulous jewelers or gemologists,
only to have CZ put in the same mountings and returned to them. There have been a number of cases of people looking at diamonds in a jewelry store, and with a quick distraction, replacing the diamond in full view of the jeweler with a CZ and giving that back instead. These will pass on sight. How do you tell a CZ from a diamond? Well, luckily technology has come to the rescue.
There are a number of devices on the market that, for under $150, will electronically test the material to see if it is a diamond or not. Diamonds
have unique electrical resistance patterns and CZ have their own. These devices are simply touched to the material in question and will tell if it is a diamond or a CZ. It is a good thing to have on hand if one plans on dealing in gems.
There are a couple of different systems for forming synthetic rubies and emeralds. One is to use a seed chip of the natural stone and then combine chemicals, heat and pressure to “grow” rubies and emeralds. The latest processes are known as flux processes, which combine heat and/or pressure to work on the ingredients composing the gemestone to be synthesized. (The ingredients are fairly easy to come by; i.e., carbon for diamonds or beryl for emeralds.)
These flux processes are designed to produce richly colored stones and almost
always do. They usually have greater clarity than the natural variety although
sometimes offer distinguishing inclusions which telltale their origin.
The most famous emeralds are probably Chatham synthetics which grow in a
group of crystals. They were first grown in 1935 by Caroll Chatham of San Francisco. The Chatham family still grows these gems but doesn’t care to discuss the process. The Chatham emerald sometimes has small spicule
inclusions on the face of the facets as a result of the crystal forming solution.
Gillson is another variety of snythetic emerald. There is also a Japanese gentleman by the name of Kazuo Inamora, President of Kyoto Ceramics, who has three showrooms in Japan and one in Beverly Hills selling “created” rubies
and emeralds. These created stones have caught on quite well in other countries including Japan and may or many not catch on here.