The Mogok Valley in Upper Myanmar (Burma) was for centuries the world’s main source for rubies. That region has produced some of the finest rubies ever mined, but in recent years very few good rubies have been found there. The very best color in Myanmar rubies is sometimes described as “pigeon’s blood.” 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) located in the northern state of Kachin.
Rubies have historically been mined in Thailand, the Pailin and Samlout District of Cambodia, Burma, India, Afghanistan, Australia, Namibia, Colombia, Japan, Scotland, Brazil and in Pakistan. In Sri Lanka, lighter shades of rubies (often “pink sapphires”) are more commonly found. After the Second World War ruby deposits were found in Tanzania, Madagascar, Vietnam, Nepal, Tajikistan, and Pakistan.
A few rubies have been found in the U.S. states of Montana, North Carolina, South Carolina and Wyoming. While searching for aluminous schists in Wyoming, geologist Dan Hausel noted an association of vermiculite with ruby and sapphire and located six previously undocumented deposits.
More recently, large ruby deposits have been found under the receding ice shelf of Greenland.