Rubies are considered one of the most valuable and expensive of colored gemstones in the world “the king of gemstones” possessing everything one would hope to find in a gemstone. it’s rarity, color, hardness, and fantastic brilliance is what makes the ruby the undisputed king of the gem world. Large rubies are harder to find than large diamonds, emeralds and sapphires. As a result, rubies’ value increases with size more than any other gemstone.
Rubies originally were discovered in India but today can be found in Myanmar (Burma), Thailand, Sri Lanka, Madagascar, Vietnam, Afghanistan, Kenya, and Tanzania.
Rubies are red corundum (all other colors of corundum are sapphires) and are one of the hardest minerals known to man next to a diamond.
Choosing A Ruby
Most important when choosing a ruby is color. Transparency is secondary so inclusions do not usually impair the quality of the stone. A ruby is a pink to blood-red colored gemstone – the most desirable color is the “pigeon’s blood”, a pure red with a hint of blue. After color follows clarity: similar to diamonds, a clear stone will command a premium, but a ruby without any needle-like rutile inclusions may indicate that the stone has been treated.
Cut and carat (weight) are also an important factor in determining the price as well as origin.
All natural rubies have imperfections in them, including color impurities and inclusions of rutile needles known as “silk”. Gemologists use these needle inclusions found in natural rubies to distinguish them from synthetics, simulants, or substitutes. Usually the rough stone is heated before cutting. Almost all rubies today are treated in some form, with heat treatment being the most common practice. However, rubies that are completely untreated but still of excellent quality command a large premium.
Some rubies show a 3-point or 6-point asterism or “star”. These rubies are cut into cabochons to display the effect properly. Asterisms are best visible with a single-light source, and move across the stone as the light moves or the stone is rotated. Such effects occur when light is reflected off the “silk” (the structurally oriented rutile needle inclusions) in a certain way. This is one example where inclusions increase the value of a gemstone. Furthermore, rubies can show color changes — though this occurs very rarely — as well as chatoyancy or the “cat’s eye” effect.
Fine rubies are typically sold as being either from Burma or not from Burma. At the epicenter of the world market in two important areas, color and price, Burma rubies hold an unprecedented allure for buyers, despite (or perhaps because of) limited production and a huge reliance on smuggling in order for gems to reach the outside world. The world trade reveres “Burma red,” or “pigeon blood” found in the Mogok valley of Upper Burma as an almost mystical standard. This special appeal determines price. When two rubies of comparable quality are offered for sale, the one from Burma often fetches twice as much. Buyers should ask where a ruby under consideration originated.
A major contributor to the allure of Burma ruby color is fluorescence. Trace amounts of chromium (sometimes less than one percent) are responsible for the red color in rubies. This impurity also causes rubies to fluoresce under ultraviolet light or even sunlight, giving Burmese rubies, which contain more chromium than most others, their appealing red glow. Some Thai rubies may actually be redder than Burma rubies, but lack the same fluorescence.