10 Dollars - Elizabeth II Posthumous, Most Important Investment Coins

The "Most Important Investment Coins" series from the Solomon Islands is a licensing arrangement in which the islands' nominal issuing authority is used almost entirely for marketing purposes — actual production is handled by a European private mint, and the coins are sold directly to collectors rather than entering any circulation channel. The extreme disproportion between this piece's 45 mm diameter and its 0.31 g gold content makes it functionally a collector medallion with legal tender status attached as a sales tool.