Quality of Mined Diamonds

Many diamonds are mined in the world each year, however less than half of these diamonds are of gem making quality. The remaining diamonds fall into the categories: near-gem quality and industrial quality. Gem quality diamonds display the qualities of excellence that are used in jewellery.

Near-gem quality diamonds will be used depending on the individual stone, as these stones may vary between industrial to diamonds with visible inclusions. Industrial quality diamonds are the stones that are considered of low quality and are suitable only for industrial use, like in the drill that dentists use.

Diamonds which have been prepared as gemstones are sold on diamond exchanges called bourses. There are 26 registered diamond bourses.

The Two Methods of Diamond Mining

There are two main methods for diamond mining. Firstly; pipe mining and secondly; alluvial mining. In pipe mining, the earth is crushed and flushed with water as it moves onto conveyor belts through tubes. The washed diamond matter is then released onto greased belts. Any diamonds will stick to the grease whereas other matter will be washed away. Recovered diamonds can then be used for the creation of gems. In the alluvial mining process, bulldozers are used to place sand directly into washing plants for processing. Alluvial mining is less costly than opencast pipe mining.

The seven largest and most productive mining sites in the world are distributed among the seven big diamond producing countries. Australia, Zaire, Botswana, South Africa, Russia, Namibia and Angola. Only estimates of diamond production numbers are available for countries like Zaire and Russia, as the governments in these countries do not publish exact figures. Diamond production in the Tshikapa and Mbuji-Mayi diamond regions in Zaire is estimated to be 17 million carats, however only 5 percent of this figure is considered to be of diamond quality making.

The Mirny Diamond Mine in Russia

Russia is another country where estimates of diamond production are only available. Mining in Russia is very costly as the ground is subjected to frost in the winter months with temperatures dropping to minus 60 degrees centigrade. It is believed that Russia has produced more than 100 million carats since World War II.

Russia's Mirna diamond mine (or Mirny diamond mine) is the largest open diamond mine in the world. It is 525 meters deep and 1,200 meters in diameter.

In the Spring of 1955, a young geologist, Yuri Khabardin, came across Mirny which was a fox's hole in a ravine with blue earth. He discovered that it contained high diamond content and with excitement he sent a message over his shortwave radio indicating in code: "I am smoking the pipe of peace". In Moscow the prearranged code was comprehended to mean that the geologist had discovered and tested a kimberlite pipe.

The volcanic pipe that Khabardin discovered was named Mirny to mean that it was a "peace" pipe. The mine was opened in 1957 and it is now exhausted. The history of the Mirny open mine indicates that before Mirny could begin producing diamonds, engineers in Siberia had to explore ways to overcome the harsh conditions at the mine site. During the long Winter in Yakutia, engineers found that the steel tools became so brittle that they broke like match sticks. To make matters more complicated, when the Summer came, the top layer of permafrost melted creating a swamp of thick mud. Despite these obstacles of nature, engineers transformed Mirny into an open-pit mine.

In 1962, the Soviet Union agreed to sell all of its uncut diamonds to De Beers. Over the following years, diamond production reached nearly ten million a year and diamonds as a result became the leading Soviet cash export to the West. In 1968, Viktor 1. Tikhonov, the head of the Mirny Diamond Administration, said: "We call ourselves the country's foreign exchange department".

In London, in the interim, the De Beers' executives were beginning to be puzzled about the increasingly large amounts of diamonds being shipped from Russia each year. More specifically, the geologists at De Beers questioned how this mine could produce five times the number of diamonds of comparable South African mines. For example, in the year 1978, the Finsch mine that went into production at roughly the same time as Mirny and covered an area more than twice that of Mirny, produced about two million carats of diamonds, whereas Mirny being much smaller produced more than ten million carats of diamonds. This was a staggering amount!

Russian geologists when quizzed about this mysterious production from Mirny, suggested that Siberian ore had an extraordinary high grade of four carats a ton. As a result this number far exceeded any grade of ore in the history of diamond mining in South Africa.

The other puzzling issue is that in South Africa following a few years of high production, all the pipe mines enter a phase of gradual decline. However after ten years of intensive excavations at Mirny, the production of diamonds instead of decreasing accelerated. Mirny continued to be a mine of mystery and awe for many years.

Today although the Mirny open mine is now exhausted its mystery and history remains and will continue to be an interesting phenomenon in diamond research and information.