A Victorian 9ct yellow gold Regard locket. REGARD is spelt out by the gemstones. Ruby, Emerald, Garnet, Amethyst, Ruby and Diamond. However, in this case, all the gems are imitated using Paste. The locket has been bloomed, which means the outer gold is 24ct and thus very gold coloured.
Paste is an old form of glass. It is a heavy, very transparent glass with a high lead content that simulates the fire and brilliance of gemstones because it has relatively high indices of refraction and strong dispersion (separation of white light into its component colours).