4 Dollars - Elizabeth II Dolphins

Cook Islands has issued small-denomination gold pieces under New Zealand's monetary umbrella since the 1970s, largely as bullion collectibles rather than anything intended for domestic circulation — the islands' actual economy runs on the New Zealand dollar. The $4 face value is a deliberate oddity, chosen to differentiate these fractional gold issues from the standard $1, $5, and $10 denominations that crowd the commemorative market.