The gemstone ruby is the red variety of the mineral Corundum, the second hardest natural mineral known to mankind. Ruby is the July birthstone, and the Capricorn Zodiac stone. Ruby has been associated with the values of love, success, integrity, passion, and promise. All colors of corundum other than red or white are called Sapphire The red color in ruby is caused by trace amounts of the element chromium. The best shade of red for ruby is often given the name "pigeon blood red", but ruby can be any shade of red up to almost pink. Oriented rutile crystal inclusions cause a six-rayed-star light effect (called asterism) to form the popular Star Ruby. Rubies come from all over the world but good gemstones are found at Thailand, India, Madagascar, Zimbabwe, North Carolina in the U.S., Afghanistan, Pakistan, Sri Lanka, Kenya, Tanzania, Kampuchea, and perhaps most notably, Burma. Like most gemstones from the antiquities, Ruby is one of the Biblestones. In Exodus, the Breastplate of Aaron is described as containing a "sardius", the ancient name for ruby.