The best place to buy gemstones is probably Africa. While the cost of gemstones from traditional sources, such as Burma, is now astonomical, it is possible to buy high quality gemstones from Africa at a reasonable price.
The main gemstone producing countries are in southern and eastern Africa, stretching from Namibia in the southwest through Zimbabwe, Mozambique, Malawi and Tanzania to Kenya in eastern Africa. Madagascar, the large island off the coast of Mozambique, is geologically part of this same gemstone-rich area, known as the Neoproterozoic Mozambique Belt.
The most important producers recently have been Tanzania, Mozambique and Madagascar. Madagascar is famous for recent discoveries of ruby and sapphire, though a number of other gemstones have been found, including tourmaline, aquamarine, chrysoberyl, andalusite, apatite, citrine, iolite and kyanite. Tanzania has enormous potential and gemstone mining there already employs more than a half of million small-scale miners throughout the country.
Mozambique is producing excellent tourmaline in a wide range of colors and has recently become famous for its high quality paraiba tourmaline; most of the world's supply of paraiba is now coming from Mozambique since the Brazilian supply is so limited.
Nigeria, the large west African nation, is the one important gemstone producer not in the Mozambique Belt. Nigeria has produced respectable blue sapphire as well as large quantities of fine tourmaline. Nigeria is also known for pyrope and almandine garnet, aquamarine and topaz.
The best way to buy gems is to find one or more reliable suppliers and buy soley from them. Initially check out the supplier and then buy a small quantity of low value stones. If he/she is trustworthy then build a long term business relationship with this person.