Ruby (Corundum)

 

Ruby is one of the best gemstones for jewellery. Ruby is a tough mineral. The hardness is second only to Diamond.  

The color of ruby is a pink to blood-red colored gemstones. The brightest and most valuable "red" called pigeon blood-red. This gems color quality has the most expensive prize.

Crystal Structure
Trigonal

Composition
Aluminium Oxide

Hardness
9

Some rubies show a a very nice asterism or "star" effect, 3 points or 6 points. These rubies are cut into cabochons shape to show the asterism effect accurately. The effect is best observable 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 effect increases the prize of the ruby.

Most of best quality ruby were found in Myanmar / Burma. The rich mineral deposit of Mogok, Burma
has produced some of the finest rubies in the world. The very best color in Burma rubies is sometimes called as "pigeon's blood ruby." In central Myanmar, the area of Mong Hsu began producing rubies during the 1990s and rapidly became the world's main ruby mining area. The most recently found ruby deposit in Myanmar is in Namya (Namyazeik).

Source: Cally Hall (Gemstones), many souces