Topaz
Though it can be found in almost every color, the most prized hue of topaz is referred to as imperial topaz. A rare type topaz ranging from yellow to reddish orange in color, this shade of topaz derives its name from its association with the Russian Czars of the 1800s.
In antiquity all yellow gems were referred to as topaz. Today our more discriminating definitions of gems allow us to identify a wide spectrum of colors as topaz. In fact, topaz in its purest state is colorless and in antiquity was sometimes mistaken for diamonds. Colored varieties include the classic spectrum from yellow through sherry orange as well as blue, pale green, pink and red, but some of these colors are unstable and can fade.