What is London Blue Topaz?
By Jared James · Last updated 21 May 2026
Definition
London Blue Topaz is the darkest and most intensely saturated variety of blue topaz, showing a deep steely blue with subtle grey or green undertones that distinguish it from the paler Swiss Blue and the bright, lighter Sky Blue varieties. The colour is not naturally occurring in this form: natural topaz is treated with irradiation and heat to produce the deep blue tone. London Blue is popular in rings, earrings and pendants because its depth of colour works well in both silver and gold settings, and it is an affordable alternative to blue sapphire.
Frequently asked questions
- What is the difference between London Blue, Swiss Blue and Sky Blue topaz?
- Sky Blue is the palest and most washed-out of the three, Swiss Blue is a bright, vivid mid-tone blue, and London Blue is the deepest and most heavily saturated, with a darker, slightly grey-green cast. The three names describe the depth of colour rather than the origin.
- Is London Blue Topaz a natural gemstone?
- Topaz itself is natural, but the deep blue colour is created through controlled irradiation and heat treatment of natural colourless or pale topaz. The treatment is permanent and widely accepted in the trade; it is fully disclosed and considered standard practice.
- Is London Blue Topaz a birthstone?
- Blue topaz, including the London Blue variety, is recognised as one of the birthstones for November alongside citrine, and is also associated with December in some modern birthstone lists. It is a popular choice for November birthdays who prefer blue to orange.
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