500 Dollars - Charles III Purely Brilliant

The Royal Canadian Mint has produced diamond-set bullion and collector pieces since the early 2000s, but embedding five Ideal Cut diamonds — a cut standard developed by Marcel Tolkowsky in 1919 specifically to maximize light return through precise angular geometry — into a 24-karat mount on a .9999 gold coin pushes the format into jeweler's territory rather than numismatic. Tolkowsky's proportions remain the benchmark against which modern diamond cutting is still measured.