50 Pence - Elizabeth II Stephen Hawking, Gold Proof

Issued the year after Hawking's death in March 2018, this piece was part of the Royal Mint's Innovation in Science series — a program that had already commemorated Isaac Newton and Charles Darwin. Hawking's inclusion prompted some debate, given that his most significant theoretical work on black hole radiation remains experimentally unconfirmed; the Royal Mint was, in effect, honoring a reputation as much as a proven body of discovery.

Struck in 22-carat gold at a modest 15.5g, the specification mirrors the standard half-sovereign planchet weight — a practical choice that kept production costs predictable within an existing infrastructure.