Sky Blue Topaz Gemstones Hardness 8.0. Topaz and citrine are the birthstones of the month of November.
Some blue topaz are indistinguishable from aquamarine with the naked eye.
Most blue topaz is irradiated and heat treated silver topaz , although it is sometimes found naturally. Appearance Sky blue topaz is the lightest shade of the blue topaz , and is often mistaken for aquamarine . Enhancements Blue topaz is usually irradiated and often heated to produce blue color. More information on gemstone enhancements. 1995-2000 Gem Hut.