Its dramatic fiery red colour has ensured that ruby has been one of the most popular gemstones throughout history. Ruby is one of the rarest of the better-known gemstones, being far rarer than diamond. There is evidence that ruby was being bought and sold in the gem markets of ancient Babylon, around six thousand years ago. Good rubies will range in colour from dark red to reds with a secondary blue, pink or orange tone, with the best being a highly fluorescent red of high intensity.
Long associated with love, passion and romance, the ruby is also the stone traditionally used to celebrate the fortieth wedding anniversary and is the birthstone for July. Rubies, like sapphires, have a hardness of 9 on Mohs scale, and as such are extremely suitable for engagement rings and jewellery for everyday wear. Rubies never go out of style.
Ruby is a variety of a gemstone known as corundum, of which sapphire is another variety. Pure corundum is colourless and the ruby is coloured with trace element of chromium. To be classified as a ruby, the stone must be a distinct, saturated red and may have a slight secondary colour, such as orange, pink or brown. The name ruby comes from the Latin rubeus, meaning red, and before the year 1800 all red gemstones, including garnet and spinel, were called ruby. If a ruby is heavily included with rutile and the crystal is cut correctly, the stone will show Asterism, or a reflective star effect, very rare and highly prized.
As with any gemstone, ruby quality varies from the very high to the very low. A good ruby will have a strong, saturated colour with minimal inclusions, unless it is a Star Ruby.
Heat – Almost all natural rubies are heat treated to minimize microscopic inclusions and even out colour resulting in a brighter stone. A high percentage of rubies are treated in this way and so you will always assume the stone has been heated. Untreated stones that are also bright and clean are highly prized and always cost more than a heated stone of similar appearance. There are a number of other treatments that are used to enhance ruby. Glass filled and flux healed rubies are prevalent in the market and care should be taken when buying a ruby that these treatments are fully disclosed.
In history, all red stones including rubies, were grouped under the name “Carbuncle”. Ruby has a long and distinguished history, being revered by the ancient people of India, who believe that rubies are the blood of a slain demon god, and statues of Buddha are usually adorned on the forehead with a ruby, as red is also the symbol of his reincarnation. The Burmese once believed that if a ruby was worn under the skin in battle, it would render the wearer invulnerable to sword and spear. The ruby is synonymous with fire, passion and erotic love.
One of the great advantages of ruby is its durability. It can be safely cleaned with any detergent and is suitable for ultrasonic cleaning. Rubies with prominent inclusions are more likely to break if subjected to a sharp of heavy knock, however all ruby should be treated with sensible care. Facet edges and surfaces will eventually be damaged after years of rough treatment. Also consider that a setting needs occasional maintenance to avoid the possibility of it loosing its grasp on your precious treasure.
Chemical Composition Al2O3 (Aluminium Oxide)
Crystal System Trigonal
Refractive Index 1.762 - 1.770
Specific Gravity 3.95 - 4.10
Fracture Conchoidal, uneven
Lustre Vitreous to subadamantine