We have had an interesting specimen to identify, bought in India some 40 years ago, beautifully carved into a small Buddha head. The specimen was extremely hard and must have been carved by someone very skilled because it is only about 3 cm high.
We identified the stone as corundum, the scientific name for rubies and sapphires. Gem quality corundum is diagnosed as ‘ruby’ if it is red. All gem quality corundums which are not red are called sapphires even the pink ones like this Buddha!