Silver coins are much sought after by coin collectors, but these are struck by the US Mint; like the American Silver Eagles, which is legal tender with a $1 face value. Besides the American Silver eagles, there exists a market that sells inexpensive Silver Eagles; these come from the private mints that sell silver coins just like the US Mint and they have their weight and purity stamped on them. However, the term coins is used only for government issued legal tender and therefore the privately owned mints sell silver rounds, the term round is used for bullion from private mints.
Just like the American Eagles, these one ounce rounds are 999 fine. The premium on privately minted is however not as much as on the American Silver Eagles.
The silver rounds struck by private mints are generally bought for investment purposes rather than for the beauty and rarity of the coins. These investment grade silver rounds have a small premium on them, and some private mints have built up a reputation for quality rounds like EngelHard, SilverTowne, NorthWest Territorial Mint, Pobjoy Mint, and Golden State Mint among others.