20 Dollars - Charles III Williamson Diamond Brooch

The Williamson Diamond — a 23.6-carat pink diamond unearthed in 1947 at John Williamson's Mwadui mine in Tanganyika — was presented to Princess Elizabeth as a wedding gift that year and later cut and set into a brooch by Cartier. It remains one of the finest pink diamonds ever recorded, notable for its exceptional saturation and near-flawless clarity. The original Cartier setting places a single brilliant-cut stone at the center of a stylized flower mount.

This coin reproduces that brooch in miniature relief, with a rhodium-plated setting and colored glass approximating the original gem's hue.