Additional information about diamonds:
1. Diamonds are pure crystallized carbon. In its rough state, it may seem of little value.
Stylus is the instrument used in testing diamonds. It is a blunt instrument with a tip called CORUNDUM. Being the hardest of all minerals, diamond can even resist the pointed tip of the stylus. Press against a genuine diamond, the tip of the stylus slides. But rub against a fake diamond, the tip produces friction.
2. Rough Diamonds:
A diamond in the rough is still diamond no matter how irregular its shape appears to be. Rough diamond crystals are classified as follows:
a. Stones and shapes (octahedron or unbroken crystals of irregular shapes)
b. Cleavages (broken crystals of irregular shapes)
c. Macles (triangular twin crystals)
d. Flats (this broken crystals with two flat parallel sides)
3. Diamond cutting
It is the way a rough diamond is cut that gives its beauty, sparkle and value. Cutting diamond is a big industry. A number of countries are known for their specialization in cutting and polishing diamonds. But there are only 4 major cutting centers in the world, namely Bombay, New York, Antwerp and Tel Aviv. However, South Africa, Holland and Brazil are also emerging as important cutting centers. Diamond cutting is also a growing industry in Russia.
Steps in cutting a diamond:
A. The first step consists of examining the stone to determine how it should be cut. A tool called loupe is used in this process which only takes few minutes to do.
There are two factors to consider in this stage: first a rough diamond loses more than half of its weight during the cutting process, and second, the position and direction of the cutting should allow for the maximum passage of light into the stone. A cutter should always bear in mind that it is the flow of light into the facets or stone cuts that gives a diamond its intricate sparkle.
B. The diamond is marked with Indium ink to indicate the divisions or cutting lines. This stage is called cross working. An octahedron, for example, is divided in the middle, and then both parts are cut into a round shape. The cuts or facets are ground and checked carefully to guard against cutting away too much stone. A diamond with only 18 facets is called single cut.
C. For a 58 facet diamond, the final cutting stage is called full brilliant cut. Here,
40 more facets are added to the 18 facets of a single cut.
D. The final process is the polishing of a cut diamond. It is considered a long
exacting and expensive process. The shape of a polished diamond is also called a cut.
(From manual of jewelries)
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