100 Dollars - Charles III 1st Portrait - Wonders of Australia - Gold Proof Opal

Opal inlay coinage has been part of the Perth Mint's production repertoire since the early 2000s, but the technical challenge of setting natural opal — a stone notorious for its fragility and sensitivity to pressure changes — into a struck gold blank without fracturing the stone has never been fully routinized. Each piece requires individual handling at the inlay stage. The result is that no two coins in an opal series are visually identical, which creates an odd tension with the uniformity proof coinage is meant to achieve.

This is also among the first Perth Mint issues to carry the effigy of Charles III rather than Elizabeth II.