According to legend, the great serpent Naga created rubies in the third egg she laid. The first egg birthed Pyusawati, the King of Pagan. Rubies are the red variety of the mineral corundum, the second hardest natural mineral. All non-red varieties of corundum are called "sapphire." Because of their hardness and resistance to abrasion, the uses of rubies, aside from their ornamental value, are extensive.