Shrouded in myths and legends, rubies are one of the world’s most expensive gems per carat. Their cost increases even faster in comparison with sapphires and emeralds. It is connected with a rarity of big natural rubies.
Rubies are red colored gemstones with pink, purple and orange hues. The most expensive and valuable color of natural ruby is true red. In marketing the most beautiful and alluring rich color is called “pigeon’s blood”. According to gemological research GRS laboratory, such stones have medium and strong fluorescence. It originates from ultraviolet rays and enhances the beauty of bright red color in the sunlight or by the light of incandescent lamp.
For many centuries, the most precious and luxurious stones have been mined in Myanmar (Burma). Natural rubies having “pigeon’s blood” color and Burma origin (the Mogok Valley and the area of Mong Hsu) are incredibly expensive ones. As you know, on the 1st December 2015 at Christie’s auction there was a new record price set for rubies 1 222 200 US$ per carat. 15,04 carat stunning gemstone “Crimson Flame” was sold for 18 382 385 US$. It is the second most expensive ruby in the world after 25,59 carat ruby called “Sunrise” sold in May 2015 for 30,3 million US$. These gemstones have reports from respectful laboratories that highlight excellent purity and the best color for rubies – “pigeon’s blood”, they also remark its Burmese origin and absence of treatment.
However, in recent years the supply from this field has dwindled. Today stones from Mozambique take a considerable part of the world market. Among Mozambique rubies there are some specimens that do not concede Burmese rubies. Also rubies are mined in Thailand, Madagascar, Tajikistan, Tanzania, Vietnam and other countries. Rubies from India can reach a big size, but they usually have poor clarity.
It is typical for rubies that most of them undergo treatment that is aimed to improve color and clarity of stones. The most widespread kind of enhancement is heat treatment. Rubies are heated in special furnace of a temperature of about 800-1900 °C. As a result of heating the color of natural stones can get more saturated, it is even possible to lighten too dark stones or remove undesirable tinges. About 90% of all mined rubies have heat treatment.
Also the cheapest treated rubies are heated ones with lead glass filling in the fractures. Such action conceals fractures in rubies, and that is why transparence of the stone improves and color gets also brighter.
A lot of gemstone lovers prefer rubies with an optical effect, called asterism. So, such stones have a star with six points that skims on cabochon’s surface. Another quality is a cat’s eye effect, here we can see a white stripe. Both these optical effects are connected with the presence of rutile needles, such samples are not heated, otherwise these inclusions will dissolve because of treatment.
Any ruby you choose, it is a fascinating stone with a rich history and it will bring its owner great mood by all means.
In addition clarity affects the price of the stone. In other words, how many inclusions and flaws it contains, and how they can be seen with a naked eye or with a 10x loupe. If a natural ruby has gorgeous color, its clarity is not so important. But if internal qualities are very noticeable, such stones will be considerably cheaper.