50 Pence - Elizabeth II Britannia, Gold Proof

The Britannia bullion and proof series was relaunched in gold in 1987, initially with a .9167 fineness deliberately chosen to match the historic crown gold standard used in English coinage from the Tudor period onward. That fineness — 22 carat — was a conscious rejection of the .9999 standard adopted by competitors like the Canadian Maple Leaf, prioritizing hardness and scratch resistance in a coin intended to actually change hands as bullion.

By 2019 the series had incorporated a rotating array of security features, including a tincture line effect milled into the surface that shifts under light — a direct response to sophisticated counterfeiting operations targeting the Chinese bullion market in the mid-2010s.