That is a nice little vse. It could also have been used in the watch making/repair trade as well as jewelry - if there are no teeth on the jaws.
I'm a nut about early vises. Most of mine are probably early to mid 19th century, but I've got a few that are or could be 18th century.
If you want to see some 18th and very early 19th century period engravings of tools that watchmakers, gunsmiths and many folks involved with any of the more precise metal working trades used - the gun shop at Colonial Williamsburg suggested this book and I could not agree more. It gave me more than a few really good ideas over the years and of course, I use it to reference 18th century tool designs.
A Catalogue of Tools for Watch and Clock Makers. By John Wyke
Here's a link that shows some of the engravings and I think most will get a kick out of seeing the screw plates and taps:
http://www.davistownmuseum.org/bioStubs.htmHere's where you can buy the book, if interested (and I'm in no way connected with them).
http://www.thebestthings.com/books/wyke.htm