Topaz is a very hard gemstone that ranges in color from brown, to yellow to blue to pink. Pink topaz is usually created by irradiating common yellow topaz. Other colors are often created by heat-treating and/or irradiating topaz. Imperial topaz is golden orange-yellow topaz; it is the most valuable topaz. Topaz may have been named for the legendary Topasos Island in the Red Sea. Legend says that topaz has the power to dispel enchantment. The ancient Greeks believed That topaz could increase strength and make a wearer invisible in times of emergency.