New Zealand's Reserve bank issues multiple sets of coins each year for a commemorative purpose. These coins are often large and are come in various types. For Example, in 2008 New Zealand post was selling (on behalf on the reserve bank) Hamilton frog commemoratives. The Hamilton's frog coins came in Brilliant un-circulated, and silver proof. The Brilliant un-circulated are highly polished, and silver proofs are made of sterling silver with various levels of polishing and frosting.
Commemorative Coins are sold at a premium price to collectors. Often, they have a high face value such as $5, $10, $20 or even $150. The coins are legal tender, but not issued for circulation.