What is blue topaz?
By Jared James · Last updated 21 May 2026
Definition
Blue topaz is topaz that starts out colourless or pale brown and is irradiated and then heated to produce its characteristic blue colour, a process that has been standard in the industry since the 1970s and is considered permanent. It comes in three recognised shades: sky blue, which is the palest and most delicate; Swiss blue, a vibrant medium blue; and London blue, the deepest, most ink-like tone. It is a November birthstone alongside citrine, and is popular in jewellery for its strong colour and relatively affordable price.
Frequently asked questions
- What are the different shades of blue topaz?
- The three main commercial grades are sky blue, a soft pale blue similar to aquamarine; Swiss blue, a bright medium blue that is the most vivid of the three; and London blue, which is a deep, steely or inky blue. London blue is generally the most expensive of the three.
- Is blue topaz treated?
- Yes, virtually all blue topaz on the market has been irradiated and heat-treated. Natural blue topaz exists but is very rare. The treatment is stable, considered permanent, and is universally accepted in the trade.
- Is blue topaz a birthstone?
- Blue topaz is recognised as one of the birthstones for November, sharing the month with citrine. It is also associated with December in some older lists. It is often given as a fourth wedding anniversary gift.
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