Ruby is a red variety of the mineral corundum and is colored by the chromium. It is a 9 on the Moh's scale of hardness making it a great choice for all types of jewelry.
Ruby is one of the most rare and valuable gem stones with the most expensive ever sold being 32.4 million dollars for a 25ct ruby ring or over 1.25 million a carat!
It's name in sanskrit is Ratnaraj and means "King of Gems" and has been mined since at least 600 AD in Burma. Rubies were traded on the ancient "Silk Road" and have been mined since truly ancient times.
Ruby is the birthstone of July and will glow under long wave fluorescent light.