A ruby is a pink to blood-red colored gemstone, a variety of the mineral corundum (aluminium oxide). Ruby is one of the most historically significant colored stones. It is mentioned four times in the Bible, in association with attributes like beauty and wisdom. In the ancient language of Sanskrit, ruby is called ratnaraj, or “king of precious stones.”
The name ruby comes from the Latin word ruber, which means “red.” The glowing red of ruby suggested an inextinguishable flame burning in the stone, even shining through clothing and able to boil water.