によってレビュー Andreas Zabczyk Nov 30, 2007 更新しました Apr 23, 2019
Sources for Fine Ruby Gems
Ruby, the red version of the mineral corundum, has long been treasured as one the rarest and most valuable of all gemstones. Admired for its hardness and brilliance, it is the rich red color that appeals to elements of the human psyche; warmth, passion and blood.
Since ruby is so rare, where does the world get its supply? What is the source of the finest ruby, and how do rubies from different parts of the world differ?
Rubies from Burma and Chanthuburi
The most valuable rubies come from Burma, which is now known as Myanmar. The region famed for the very finest rubies is the Mogok Valley, located about 200 km northeast of Mandalay. It is believed that ruby mining here has been active for more than a thousand years, and this is the source of the rare "pigeon's blood" ruby. The best Burmese rubies have high color intensity and a fluorescent quality where the gem actually appears to glow. Some very fine specimens also have a velvety softness due to tiny inclusions of rutile that are known as "silk" in the trade.
While Mogok is by far the most famous location in Burma for fine rubies, most of the Burmese rubies found today actually come from a different location - from Mong Hsu in the Shan State. The Mong Hsu deposit was discovered only in 1992, and the deposit was so large that it was hailed as the most important discovery of Burmese ruby for thousands of years. But these Mong Hsu rubies were not the same quality as the famed Mogok rubies; they tended to have a slightly bluish or purplish hue which was not as attractive. The color can be improved by heat treatment, so virtually all the Mong Hsu ruby on the market has been treated.
Prior to the discovery of the Mong Hsu ruby deposit, there was a long period when virtually all the world's supply of ruby came from locations outside Burma. In 1962, there was a military coup in Burma led by Ne Win, and the military took control of the Mogok ruby mines. Burma was virtually closed for decades as Ne Win pursued his own bizarre brand of socialism. Thus the world was forced to look elsewhere for ruby. They looked to Thailand, because Thailand had the largest supply of facetable material.
Rubies from Burma
The Thai rubies came from Chanthaburi Province, an area of Eastern Thailand bordering Cambodia. The Thai rubies had a very different look from the Burmese rubies. Though the Thai rubies had excellent clarity, they had a high iron content, which rendered them a dark garnet-like red. The Chanthaburi gem industry discovered that the color could be improved with heat treatment, and the Thai rubies went on to have major market success. For many people, the clear, deep red of the Thai ruby is the quintessential ruby look, yet those who know the fluorescent Burmese rubies would likely disagree.
Given the tremendous world demand for ruby, modern equipment was brought to the Chanthaburi mines, and by the 1980s, the mines were mostly worked out. Before long, the discovery of the Mong Hsu deposit in Burma filled the void. Then another important ruby source was discovered in 2000, this time in Madagascar.
Rubies from Mozambique and Madagascar
Two deposits in Eastern Madagascar - Vatomandry and Andilamena - have had a significant impact on the world's gemstone industry. The first Andilamena rubies were discovered in October 2000, but these were not transparent and appeared rather dark, requiring heat treatment to improve the color and remove the purple component. Better quality rubies were found in January 2001, and within 6 weeks there were nearly 40,000 miners working in the Andilamena area. Rubies from this region occur as well-formed tabular crystals (which average 0.5 of a gram or 2.5 carats each) with slightly rounded edges. Clean, attractive rubies with fine, deep red hues are rare from this deposit. However, some superb examples weighing over 5 grams have been mined.
Fine Ruby Gemstone from Mozambique
Almost ten years after the Madagascan discovery, a new ruby deposit was found across the water from Madagascar in Northeastern Mozambique. This area shares some of the mineral-rich geological features of Madagascar and has steadily been producing fine rubies that are comparable to the Madagascan rubies. Some of the Mozambican rubies have remarkable clarity and a beautiful deep-red hue. An additional new ruby source to be explored is Greenland, where ruby has also been found in recent years.
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