Rubies are a type of corundum, a rare mineral made up of densely packed aluminum and oxygen atoms, which are normally colorless. When other atoms are substituted for a few of the aluminum ones, bright hues emerge. Small amounts of chromium impart the deep red color of ruby, traces of titanium and iron produce the stunning blue of sapphire, and chromium and ferric iron create the delicate orange shades of the extremely rare and costly padparadscha.
Rubies with their fiery hearts have inspired passion and legends throughout history. Rubies are even more rare than was once believed. Since chemical testing has become more common, it's been discovered that many of the world's most famous rubies are not rubies at all, but either garnet or spinel. While still beautiful, they don't possess the hardness nor the rich depth of color found in true rubies.
The color of rubies has given rise to numerous legends, associating the gemstone with courage, power, devotion, passion and love. In Hindu lore, rubies were believed to be the crystallized blood of the demon, Vala, whose body seeded all the mines of the world. When his body was divided, his blood fell over Sri Lanka and Burma, creating the rubies that can be mined from the ground. The sparkle and luminescence of rubies is said to be created by an inextinguishable fire in the heart of the stone. The fire is linked to the life of the person who wears it or owns it, and as long as the ruby burns bright, it is said, the person will enjoy good fortune and good health. So clear is this connection, according to some legends, that a ruby will darken in color if its wearer's life is in danger. In healing, rubies are the gem of choice to cure diseases of the blood and the heart.