Collectible coins, such as the 2017 United States Proof Sets, are specially minted coins that are produced with a higher level of detail and a polished finish. These Proof Sets include a selection of standard coins from that year, typically encompassing the penny, nickel, dime, quarter (25c), half dollar, and dollar coins, all struck at the San Francisco Mint. The coins in Proof Sets are encapsulated in protective packaging and come with a certificate of authenticity, making them desirable for collectors due to their quality and limited mintage.