The Kookaburra is one of the major silver bullion coin to change its design yearly. It has been issued in four popular sizes, 1oz., 2oz., 10oz. and kilo (32.5 oz.) through the Perth Mint. The official bullion 1 oz series started in 1990. Many variations exist with extra stamps or seals (‘privies’) issued for special occasions & coin shows. The mirrored proof design of one year (issued from 1990 to 2005) became the model for the frosted uncirculated, or “specimen”, of the next. Gold plated “specimens” have been mint issued since 2004.