20 Dollars - Charles III Pompeii

Pompeii's destruction in 79 AD was documented firsthand by Pliny the Younger in two letters to Tacitus — the only eyewitness account of the eruption to survive antiquity. Excavation of the buried city began under the Bourbon king Charles VII of Naples in 1748, making the site's modern archaeological identity inseparable from royal patronage from the outset.

Cook Islands has become a dominant issuer in the high-relief numismatic silver market precisely because its licensing arrangements with the Perth and Bern mints allow production specifications that most sovereign mints won't accommodate for standard issues. The 93.3g weight places this squarely in the three-troy-ounce category.