Quality
Pure silver, also known as three-nines grade silver, is too soft for practical use because it can easily become misshapen. It is only used to create bullion bars and select silver coins.
Function
One-ounce silver coins are uncirculated coins. This means that they are sold directly from a country's mint system to collectors. They are never circulated, or used for legal tender.
Value
The value of these coins is increased by their limited status. Coins are produced both in limited numbers and for a limited period of time, making them harder to get, and there for more expensive to procure.
Types
The most common pure silver coins sought by collectors are the American silver eagle, the Australian kookaburra or lunar zodiac-theme coins, Chinese panda, Canadian silver maple leaf, and British sovereign.