THE GEMSTONE LIBRARY
London Blue Topaz
Deep blue topaz, its trade color name, common color treatment and careful jewelry care.
A color name within the topaz family
London Blue describes a deep blue appearance used in the gemstone trade. It is not a distinct mineral species and does not mean the stone was mined in London. The mineral is topaz; the color name helps distinguish this darker blue presentation from lighter blue topaz sold under other trade descriptions.
Our March photograph shows faceted blue stones in sterling silver rings. Each setting frames the stone differently, while the facets create bright and dark areas as the hand moves. A photograph is useful for remembering the collection, but lighting, exposure and the display used to view it influence the shade seen on screen.
How blue topaz is commonly produced
GIA explains that irradiation followed by heat treatment transforms colorless topaz into commercially available blue hues. Strong blue topaz should be understood in this treatment context rather than marketed as naturally blue on the strength of its color alone. Treatment can change a gemstone’s color while the underlying mineral remains natural topaz.
The precise processing history of an individual stone belongs in its supplier disclosure or laboratory documentation. The term London Blue is a description of appearance, not an analytical record of the irradiation method, facility or treatment conditions. It also differs from the iridescent surface-coating effect commonly marketed as Mystic Topaz.
Hardness is only part of durability
Topaz ranks 8 on the Mohs hardness scale, making it relatively resistant to ordinary scratching. However, it has basal cleavage: a sharp blow can split it along a structural plane. GIA consequently distinguishes its high hardness from its limited toughness. A ring can therefore benefit from a protective setting and thoughtful handling even when the polished stone feels hard.
Care for topaz rings
Clean with lukewarm water, a small amount of mild soap and a soft brush, then rinse and dry gently. Avoid steam and ultrasonic cleaners. Remove rings before activities that can deliver blows to the stone or pressure to its mounting. Sudden temperature changes should also be avoided. Store rings separately so that the silver and the gemstone do not rub against harder objects. This approach protects both the facet edges and the setting while keeping the blue color easy to enjoy.
View this photograph in March 2025 Memory Lane →