Final answer:
Gem corundum is globally distributed in countries such as Myanmar, Sri Lanka, Thailand, Cambodia, and Afghanistan. Locally, the distribution can vary within these countries due to different geological formations.
Step-by-step explanation:
Gem corundum refers to the gem-quality crystals of ruby and sapphire. The global distribution of gem corundum is found in various countries around the world, including Myanmar (Burma), Sri Lanka, Thailand, Cambodia, and Afghanistan. These countries are known for their rich deposits of gem-quality rubies and sapphires. On a local level, the distribution of gem corundum can vary within these countries, as different regions may have distinct geological formations that are conducive to the formation of gem corundum.