Onyx is an alternate birthstone for the month of July, with ruby being the traditional birthstone.
Onyx is a jet-black gemstone, considered highly fashionable through the ages. It has been one of the most important engraving and cameo gemstones, with examples dating back thousands of years. Roman soldiers wore onyx talismans hoping that they made the wearer as courageous as the heroic warriors depicted on the gems.
Onyx is believed to eliminate negative thinking and sharpen the wits, instinct, and intuition. It is also thought to be a stone that helps to change one's habits.