500 Dollars - In the name of Elizabeth II De Beers Ideal Cushion Diamond

The De Beers partnership here is purely commercial — this is a bullion-adjacent collectible priced well above melt, marketed to buyers who want a diamond set into fine gold rather than a coin with any transactional history. De Beers' "Ideal" cut designation refers to their proprietary cushion-cut specification, distinct from the American Ideal standard developed by Marcel Tolkowsky in 1919. The Royal Canadian Mint has increasingly pursued inset gemstone issues since the mid-2000s, and the 148-gram gold weight places this firmly outside circulation reality.