The name zircon comes from the Arabic 'zargoon', meaning golden coloured. However, zircons are also found in a range of greens and browns. The lustrous colours of zircon used in jewellery are often produced by heating brown zircon. Heating the stones in an oxygen-free atmosphere produces blue zircon, which may then be heated in air to create a golden colour. Zircon displays a lustre and dispersion (fire) that rival those of diamond. Historically, colourless zircon has been used as a diamond substitute. However, although hard, it is very brittle and closer examination usually reveals damage to the surface and the facet edges. There is also a high level of double refraction, not found in diamonds. This can be seen under magnification as the back facets appear doubled.
The V&A owns an important collection of 154 gems bequeathed by the Reverend Chauncy Hare Townshend, a cleric and poet. Sir A. H. Church gave additional specimens, including this one, in 1913. He also compiled the first catalogue Precious Stones: A Guide to the Townshend Collection. The first edition appeared in 1883. The stones are mounted as rings, although they may not have been intended to be worn.