Myanmar produces many fine rubies from metamorphic deposits. Sri Lanka and Madagascar yield diverse sapphires. Colombia is renowned for hydrothermal emeralds. Australia supplies opal from sedimentary environments. Southern Africa yields diamonds from kimberlites and alluvial sources.
Other regions include Brazil for tourmaline and topaz, Zambia for emeralds, and various African countries for colored stones. Geology dictates which gems predominate; secondary alluvial deposits often provide easier recovery of durable varieties like corundum and garnet.