Rubies

Rubies are red to pink colored gemstones, varieties of corundum. The name comes from the Latin word ruber, meaning red. Other color variations of the mineral are called sapphires. Myanmar (Burma) has been the worlds main source of rubies. Other sources include Thailand, Sri Lanka, Madagascar and Tanzania. Along with diamonds, sapphires and emeralds, they are one of the four precious stones.

Color

The quality and price of rubies is most often determined by criteria known as the four Cs, the same criteria (color, cut, clarity and carat weight) used for grading diamonds. The size and geographic origin also effects the price. Color as a grading criterium is made up of three parts, hue, tone and saturation. Hue determines the basic color sensation from a gem. Tone is the lightness or darkness of the color and saturation describes how vivid or dull the color is. The finest rubies are a vivid medium-dark toned red. Pink, orange and purple are the secondary hues in rubies and purple is the preferred one among these. Rubies are often set in gold, because the saturated yellow color neutralizes the blue in purplish rubies and makes them appear a pure red.

Clarity
All natural rubies have inclusions of rutile. Treating them with heat, dissolves the inclusions improving transparency. This treatment is permanent and does not degrade over time. It is an accepted treatment and it is assumed that all rubies are heat treated unless specified other wise.  Synthetic rubies have also been manufactured since the 19^th century. Unlike natural rubies, these have no rutile inclusions and this fact is often used to distinguish between the two. They have technological uses, such as ruby lasers and can also be use in jewelry.

Cut
Transparent rubies are usually cut in to oval a cushion cuts. Rubies with a large amount of rutile inclusions exhibit the cats eye effect and if the inclusions are precisely oriented the surface of the stone will show a six pointed star (asterism). These are cut en cabochon to best display this effect.

Carat weight
Large rubies are more rare and valuable then diamonds. A ruby's weight is measured in carats. 5 carats = 1 gram.

Rubies as Gifts
Rubies are the birthstone of July and the traditional present for the 15^th and 40^th wedding anniversaries. In the Sanskrit language they are called "ratnaraj" which translates in to "King of Gemstones". Since ancient times were though to protect against misfortune and bad health and were favored by royalty. Many crowns and other royal jewelry is decorated with rubies. Although some famous rubies, like the "Black Prince's Ruby" of the Crown Jewels of the United Kingdom is actually spinel, a different gemstone. Until the beginning of the 19^th century these were thought to be rubies.

Wearing rubies
Larger oval and cushion cut rubies are often set in rings, while groups smaller round cut rubies make beautiful earrings or pendants. Paired with diamonds or by themselves, the passionate scarlet colored rubies make a great addition to any jewelry collection.