What Does ‘Fine Silver’ Mean?

By GovMint :

By definition, fine silver boasts a purity level of 99.9% or higher. Fine silver is distinguished by its high purity from other types of silver that may contain more significant amounts of other metals, such as sterling silver, which is only 92.5% pure. Fine silver tends to be the preferred option amongst collectors and stackers alike.

Sources Used:

https://www.pcgs.com/news/what-are-full-bands-mercury-dimes