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Рубин фантазийной огранки

Stones ranking second on the popularity scale after diamonds belong to the corundum group. Corundum is a word that is not usually familiar with the casual jewelry buyer, so I will explain what are they, what kinds of corunds exist, and what is the difference in quality and price amongst them.

Properly speaking, corundum is nothing but a regular aluminum oxide (Al2O3), which is very common in nature. Moreover, its constituents, aluminum and oxygen, are among five of the most common chemical elements on the planet. The Mohs’ hardness of corundum is 9, and the relative density is 4g/cm3. Rubies could have been the hardest stones if not for diamonds--excluding the scale and judging by absolute rates, diamonds are much harder. Small additions of different metallic oxides give corunds a wide color range.

A corund, with the addition of chrome--which, in fact, is responsible for the red coloring--is called a ruby. Blue coloring means that the crystal of the corundum has additions of iron and titanium. The common name of sapphire is now given to all kinds of precious corunds, except for rubies and padparadschas. Different combinations of metallic oxides like chrome, iron, titanium, and vanadium that are added to the corunds give us the wide range of sapphire colors. Naturally, there exist pink, purple, yellow, green, and orange sapphires; there are also many different variations of transitional and mixed colors that are known. But let us get back to our main character, the ruby.

A blood-colored (clear red with a slight purple hue) ruby, or red precious corund, from Burma, especially one that has not been thermally treated, will costs a great deal. This particular corundum is, in fact, the most expensive gemstone in the world. Additionally, of all the unique colored brilliants, it is the red (ruby) one that is the most expensive. A five-or six-carat crystal with the properties mentioned above costs a million dollars. Unfortunately, the stones of such size and properties are extremely rare, and in the nearest future, their prices will only rise.

rubin_02 Ruby in the rockRuby in the rock rubin_03

The ruby is the stone for a true lady, though it wouldn’t look too out of place on a true gentleman, either. Traditionally, the most expensive rubies are bought by the Arab millionaires. One must admit that to wear a ring, which can costs the same as a dozen Mercedes, is a style in and of itself. But those are just the rings; there are ruby necklaces and bracelets, too.

Natural rubies are found in very few places. The best stones on the market come from the Burmese deposits: Mogok, the largest; Mong Shu; and Namja. It is said that the deposits are almost depleted, but most probably, these are rumors that exist to make the prices higher. The Burmese governor also bears the title “The Master of Rubies,” so it is highly impossible that one day he will ever be devoid of his favorite gemstones. There is also a deposit in Vietnam, Luk Yen, where the quality and chemical composition of the stones often match those from Burma, though large crystals from Luk Yen are quite rare.

Though rubies are mined mainly by the Burmese, the trade is actually held by the local Chinese. It is very characteristic that the merchants usually act indirectly in the sale of the rubies: their wives and daughters instead represent their interests. Either it is a relaxing effect of the Myanmar culture or a smart marketing move aimed at getting more buyers, but in any case the stone dealers never complain.

The Burmese are not the only ones who mine rubies, but they are the best. African rubies are bigger, as a rule, but they have a poorer color. Arusha, the Tanzanian deposit, is known for its brown-hued rubies that cost less; also there are two Malagasy fields, Andilamena and Vatomandry. A few stones are now mined from the newly discovered deposit in the state of Kashmir, India. The first ruby there was found only in 1979. This is a highland deposit field of about 10 square kilometers. It is operable for only three months a year; during the rest of the year, the plateau is inaccessible because of the rough mountain weather and bad roads. A deposit in the Pamir mountains, in Tadjikistan, should also be mentioned. Kukurtskoye, or as it is often called, Turakulominskoye, is a deposit is situated in the East Pamir, Murghob district of Kuhistoni-Badakhshon. Nearby, there are proven fields of granitic pegmatite with topaz and jewelry tourmaline, as well as large accumulations of hydrothermal jewelry scapolite. The whole territory is called the Kukurt gemstone center.

ruby_04 ruby_06 ruby_05

Rubies are mined without any special equipment, in the way thatour ancestors did in the 13th century (the Mogok deposit dates back to that time). Most often, the stones are mined from the strata on the bottoms of rivers that outwashes the rocks. The soil is filtered manually. The only exception to these rules are the Kashmir and the Pamir deposits, where the stones are mined directly from the rocks.

Raw material is usually supplied to Thailand for processing and cutting. Only the most expensive rubies are cut in Europe and Israel. A large amount of raw material is treated by temperature of 1600–1800°C in the ambient air; as a result, from a piece of dark-purple corundum one could achieve a decent-colored ruby.

On the other hand, natural red rubies are very rare and are therefore extremely expensive. The price of a non-treated, five-carat, pigeon-blood ruby starts at 50,000 dollars for a carat. But even these stones seem to be made to sell on the market; they are so unique that there is always somebody ready and willing to buy them.

If a buyer were to say that he would like a white diamond of five to 15 carats, he would be contacted by countless diamond dealers. But if he would instead like to purchase a five-carat ruby, he would have to wait a long time, even if he announced his intention to the world. This is how rare exceptionally good rubies are.The brilliants are easy to evaluate with the Rappoport tables, where the price for a carat is defined on the basis of the color, weight, clarity, and cut. As for a precious corundum, it is quite difficult to estimate its market value. The real specialists in stones, however, are quite hard to find.

The major ruby market is situated in Asia, where they also organize the auctions of raw material. In May and September in Rangoon, the largest city in Myanmar, the Emporium auction takes place. There, they sell many corundums for thermal treatment. A great deal of stones find their way to Bangkok through the elaborate network of dealers, and it is important to note that in Bangkok, you will have a chance to buy a good stone cheaper than you can buy in Myanmar.

A ring with a luxurious ruby (11,56 ct) bought from the relatives of Bruce Lee, famous fighterA ring with a luxurious ruby (11,56 ct) bought from the relatives of Bruce Lee, famous fighter ruby_09 Non-heated pigeon-blood ruby, 5,12 ctNon-heated pigeon-blood ruby, 5,12 ct

The most expensive ruby (38 carats) I have ever seen was bought by a good friend and wonderful gemologist, Kenneth Sue, at an auction in Rangoon in 1995 for $5.86 million. The purchase was for the Chow Tai Fook Enterprises Ltd. After cutting, it weighed 25 carats, and the gem was then sold to the Sheikh of Brunei for $12 million. In 2005, the same company bought an eight-carat ruby for $2 million (its image was featured on the first page of the Sotheby’s catalog in May), and a five-carat ruby was sold at the Christie’s auction two years later for $1.75 million.

The crystals of ruby can be huge. For example, The Sun of Mogok is a giant ruby weighing 1743 carats. Fortunately, it is preserved in its natural state and is owned by the state of Myanmar, just as the famous Navara Ruby weighing 504.5 carats. Another famous ruby, the Nixon Ruby, weighs 196 carats and is preserved in the Natural History Museum of Los Angeles. The Museum of Natural History in New York has a somewhat smaller stone, “just” 100 carats, but it has a bright star that distinguishes it from its West Coast relative.

Sometimes, if a dealer insists, a buyer must fly to Myanmar. The country is quite interesting: it possesses a great deal of mineral resources, including oil and gas, but at the same time, it is extremely poor. Reasons for Myanmar’s poverty include a long-term inflation and an ineffective banking system--everything must be paid for in cash. Now can you imagine how many trunks of money one has to give for a five-carat ruby, if a dinner for four in a decent Rangoon restaurant costs a heavy briefcase of local kyats–in large bills!

Thermally treated (enhanced) rubies sometimes cost a lot, too, and a five-carat, pigeon-blood gem may cost $8,000 to 10,000 per carat. As for a unique thermally treated ruby that weighs perhaps 16 carats, its price in the end of 1999 reached $220,000 per carat.

I have already mentioned that the congress of jewelers provided a decision to make it mandatory that all gemological laboratories mention in their certificates any thermal treatment that was conducted on the gem. After that ruling, the price of the natural (non-treated) rubies skyrocketed. At the same time, however, the price of the large thermally treated stones stayed almost the same, because a ruby--regardless of whether it is treated or untreated--is still the rarest and the most sought-after gemstone in the world.

So why do rubies and their prices vary so much?

The peony decorated with a rubyThe peony decorated with a ruby ruby_10

In ancient India, they established the following system for rubies: bandula, flower-like; bahdhuyubi, gunia berry-like; sikhandika, cochineal-like; indragopi, Chinese rose-like; odrapushpaka, pomegranate seed-like; kuttima, kinsuk flower-like; parna, cinnober-like; simantaka, blood-like; raktakhuya ???. A person of today would most definitely have a hard time getting through this highly poetic table of ruby designations, so the gemological laboratories developed a simplified evaluation system (the buyer usually requires a certificate for stones weighing over one carat).

According to color and hue, rubies are classified as follows:

  • pinkish-red;
  • red;
  • intensive red
  • vivid red, pigeon blood;
  • deep red.

The most attractive color for the buyer is pigeon blood. Experienced gemologists can distinguish the various hues of rubies, the most valuable of which is the golden vivid red.

There is a delicate difference between a ruby and a pink sapphire. There is, obviously, no difference in chemical composition, and as for the color and hue, the difference is small. Yet the difference in price is huge! Different gemologists solve this problem different ways. In Thailand, for example, they say there is no such thing as a pink sapphire–which is quite understandable. But many merchants prefer to keep it unclear and use it for their own ulterior motives: they buy a pink sapphire and sell it as a pinkish-red ruby.

Usually, only transparent corunds are classified as rubies. But if the stone is asteriated, or “star-marked,” the corundum is classified as a ruby, though usually the asteriated stones are not transparent.  The same goes for the asteriated stones, even if their color is purple. In this case, the merchants use the ruby’s popularity and good reputation to encourage a sale.

All natural stones have inclusions and internal flaws that can be seen under a magnifying glass  as cracks, curtains, bubbles, blackouts, silk moire, clods, etc. After a long thermal treatment at about 1800°C, the cracks clot, the bubbles disappear, and the blackouts dissolve. Heating in a borax environment is especially effective, as it may help to improve even heavily damaged stones. Borax infiltrates the cracks and hollows inside the crystal, makes the stone transparent. That is why the stones heated in the borax environment are not valued highly by the experts. Additionally, some cutters use organic natural oils to fill in the cracks. They say it helps to considerably improve the optical characteristics of the crystals, and every three years the procedure is repeated to give the stone that sophisticated and fiery look. However, if you ask me, the effect of this “oiling” is more of a psychological nature than something real.

The price of a stone depends on how many cracks and inclusions it has, whether the cracks appear on the table (upper horizonal facet of a stone), as well as how the cracks and curtains inside the crystal are oriented and whether they interfere with the color play. The cutting of a ruby is meant to get the best color (it is different for various directions in the crystal), and only after that are the inclusions envisaged. Correct direction of the table is perpendicular to the crystal’s axis. The stone cut according to the correct direction of the internal inclusions is said to be “burning” within. Usually, when the cut is given, the owner prefers to gain in carat weight.

The Rosser Reeves star ruby, 138,7 ct was given to the Smithsonian Institute in 1965. It is reputed to be the largest and the most beautiful star ruby in the worldThe Rosser Reeves star ruby, 138,7 ct was given to the Smithsonian Institute in 1965. It is reputed to be the largest and the most beautiful star ruby in the world ruby_12 A set of stones in the casts ready to be shown to a buyerA set of stones in the casts ready to be shown to a buyer

Also, many things depend on the shape of the stone being cut. Here, the most important moment is the correct proportion of the crown (upper part) and pavilion (lower part). The more it is shifted towards the crown, the more valuable the stone. But the crystal should not be flat. One of the most serious flaws is when the stone shines through–i.e., the light comes directly through it.

There are two approaches to the cutting of precious (large and valuable) corunds:

The first approach is for the Asian market, which is considerably bigger than the European market, as it includes Thailand, Hong Kong, Taiwan, Japan, China, and India. The main task here is to preserve the ruby’s weight. It does not mean that in Asia they know nothing about good cutting; it is just believed that the jewelry piece in which the stone is set will hide all the flaws. American consumers also prefer this type of cutting, though in the long run, it is the customer who decides based on personal preference, and he sometimes decides to give the stone another cut.

The second approach is meant for the European market, where attention is paid to the correct geometry. To calculate it, they use computers. The most famous cutting center is situated in Idar-Oberstein, Germany, but places Moscow, Kiev, or Paris will also give your stone just as perfect a cut. Usually, the so-called “European” cut means serious weight loss  for a stone--about 30 percent compared to Asian cut--but considerable gain in the price per carat. Quite often, however, this approach does not work because major buyers of rubies are Asians and Americans, and they consider weight as the defining factor when purchasing a stone.

A ruby that is cut and ready to be set will lead to a serious compromise among a dozen or so different factors. The complexity of these factors--namely weight, color, presence and orientation of inclusions, cut shape, thermal treatment, etc.--defines the market value of corunds in general and rubies in particular. In November 2006 at one of the auctions in Hong Kong, two natural pigeon-blood rubies were put on sale: one, weighing 5.01 carats, was sold for $216,000 for a carat, and the other one, weighing 5.7 carats, was sold for $220,000 for a carat. But in February 2008, another record was set: at the Christie’s auction in Saint-Maurice, a ruby weighing 8.62 carats has been sold for $425,000 for a carat--$3,663,500 for the stone! It is very hard to find something in this world that could compare—other than another magnificent pigeon-blood ruby, the likes of which have not yet been found!