Topaz is the gemstone as well as the birthstone for the month of November. It occurs naturally in many colors including blue, orange, brown, green, pink, beige and red. Colorless topaz, a common variation, can be treated by irradiation to produce a wide range of shades of blue. Thus treated, blue topaz is one of the most popular and widely used of all gemstones. Blue topaz was adopted as the state gemstone as the result of legislation approved March 26, 1969.Ancient Greeks believed this stone to posses many powers, among them the ability to cure insanity, asthma, weak vision and insomnia and give its wearer the power of invisibility in times of danger.