I'm researching this big seal (45 mm) I have - obviously with Merchant monogram of 4FV. So far the "Medieval Merchant's lead seal with 4FV monogram" is the best attribution I have..
May I ask your thoughts about it?
My best wishes,
Anna
p.s. Wiki article about "Sign of Four" Merchant's marks:
http://en.wikipedia.org/wiki/Merchant's_mark