Deposit of Ruby

The host rocks of ruby are metamorphic dolomite marbles, gneiss, and amphibolite. The yield of rubies from such primary deposits is not economically profitable. Rather, secondary alluvial deposits are worked. Because of its high density, ruby is normally separated through the washing of river gravels, sands, and soil, then concentrate, and finally picked out by hand.
Production methods are still as primitive as they were a hundred years ago in many location. In state-owned mines, on the other hand, the usage of machinery is not exactly the rule, but much more frequent than in private companies. Some state regulated companies (e-g., Mogok in Myanmar) lately even work with highly mechanized machinery both above-and underground.
                                     
                                                            Mogok in Myanmar

                                                                   Rubies from Burma

Some of the most important deposits are in Myanmar, Thailand, Sri Lanka, and Tanzania. For centuries, the most important have been in upper Myanmar near Mogok. The ruby-bearing layer runs several yards under the surface. Apparently pigeon's blood color. They are consider to be the most valuable rubies of all. Large stones are rare. Mineral found together with ruby, often also of gemstone quality, are precious beryl, chrysoberyl, garnet, moonstone, sapphire, spinel, topaz, tourmaline, and zircon. In the early 1990s large new deposits were discovered at Mong Hsu in Myanmar. Rubies from Thailand often have a brown or violet tint to them.They are found southeast of Bangkok in the district of Chantaburi in clayey gravels. Shafts are sunk to a depth of 20 ft (8 m). However, in recent years Thai ruby production has been declining.
In Sri Lanka deposits are situated in the southwest of the island in the district of Ratnapura. Rubies from these deposits( called illam by the local population) are usually light red to raspberry-red. Some of the rubies are recovered from the river sands and gravels.
Since the 1950s Tanzania has produced a decorative green rock, a zoisite(anyolite), with the most opaque rubies. Only a few crystals are cuttable, most being used as decorative stones. On the upper Umba River(northwest Tanzania), on the other hand, rubies with gemstone quality have been found that are violet to brown-red.
Other mining deposits are in Afghanistan, Australia (Queensland, New South Wale), Brazil, Indian, Cambodia, Kenya, Madagascar, Malawi, Nepal, Pakistan, Zimbabwe, Tajikistan, the Unite States ( Montana, North Carolina), and Vietnam.
Small ruby deposits can also be found in Switzerland (Tessin), in Norway, and the southwest Coast of Greenland.

                                                        Ruby's deposit in Cambodia