“Medical grade” silver? No such beast, so far as I’m aware.
The flip answer is to say the difference is marketing.
Meanwhile, “Fine silver” is just pure silver. Minimum purity
999/1000 pure Ag. So there’s no percentage left to make it any
particular grade of anything except pure silver.
Sterling is 925/1000 Silver, with the remainder usually (but not
There are silver alloys with all sorts of things, including platinum.
Somebody might be calling one of those “medical” for some reason, but
there’s no official ‘medical grade’ or “jewelry grade” alloy of
silver. It’s just whatever alloy it is. Use it for whatever you like.
Now that I think of it, silver is antimicrobial, and was used to
make medical instruments of various sorts up until the 1940’s.
Depending on application, those old instruments are either pure
silver, sterling, or pure silver plated onto something. (usually
brass.) The problem with pure silver is that it’s very soft. Too soft
to be of much use by itself.
For whatever that’s worth.