Diamonds, best of all gems

Fabian H. Chandra, Gemologist, Jakarta

Answering the seemingly simple question, 'What kind of gems are found in Indonesia?', is actually quite difficult. There are lots of them but the most important are diamonds, pearls, opals, quartzes and chalcedonies.

Still, the best and most expensive is the diamond, particularly the pink diamond. This is similar to the sort found in the Argyle diamond mines in Australia's Northern Territory.

There are two diamond producers in Indonesia -- Martapura in South Kalimantan and Ngabang in North Kalimantan.

Diamonds mined in Kalimantan have relatively good clarity as they are rounded, river-tumbled stones. Therefore most of them will end up in pieces of jewelry. These diamonds are alluvial, meaning they are carried long distances by the flow of the river from its source.

Around 95 percent of Australian diamonds are of industrial quality and are not suitable for use as gems. They are normally used as industrial abrasives, in diamond drilling equipment, or in glass cutting knives.

Compared to giant producers like South Africa (with its Kimberley mine), Australia and Namibia, Indonesia is considered a very small producer. But being the 12th largest in the world -- perhaps now only 14th due to the discovery of diamond deposits in North America -- Indonesia is still a significant player.

The biggest diamond ever found in Indonesia is the Trisakti diamond, weighing in at 166.72 carats. It was found in 1965 in the Cempaka district of South Kalimantan before being cut in Amsterdam. However, its whereabouts remain a mystery even today.

Among the world's most famous diamonds are the Cullinan I or Star of Africa, which weighs 530.20 carats and is now kept in the Tower of London; the Tiffany (128.51 carats), the Koh-i-Noor (108.92 carats) and the Florentine (137.27 carats).

The price of a diamond depends on the four C's - color, clarity, cut and carat weight.

Colors range from the expensive, very fine white to the less valuable light yellow and light brown. Natural highly saturated yellow diamonds, known as canary yellow, are more expensive than colorless ones. Some of the other fancy colors that can be found are blue, purple, pink, red, orange and green. Almost every color of the rainbow is represented.

The meaning of the term "clarity" varies throughout the world. In Germany, clarity means inner perfection but in the United States and Scandinavia, clarity also takes into account aspects of the quality of the outer finish.

The third factor is the diamond's cut. Good cutting enhances a diamond's beauty. It produces effects known as 'brilliance' and 'scintillation'. Brilliance is the total white light reflected to the eye from inside the stone and its surface. Scintillation is the dynamic pattern of sparkling reflections. Most diamonds are cut in a round brilliant cut. Another popular cut is known as the fancy cut. Lately, the square princess cut has gained wider acceptance as an alternative to the brilliant variety.

Carat weight is related to size. One carat equals one fifth of a gram or 0.2 grams. The price of larger diamonds is higher as they are harder to find in nature. Sometimes the price of a carat diamond of certain quality is US$1,000 per carat.

Imagine the price of the Cullinan I (530.20 carats), which is in a pear shape, if the price of one carat of a medium quality pear shape can reach up to US$5,000 retail.

The Cullinan I is the most expensive diamond for its size. But the most expensive diamond in terms of carat weight is surprisingly small.

At the end of the 1980s, Christie's in New York auctioned a natural red diamond that weighed just 0.87 carats. The offers rose rapidly, with the price eventually reaching $1 million per carat or $870,000 for the tiny diamond. It is the most expensive gem on earth in terms of per carat weight.

As Marilyn Monroe said in one of her movies Diamonds are a girl's best friend - she might have one day referred to this diamond if she had lived longer.