As with any legal question the answer will vary with the
jurisdiction. In the United States Pawn Shops are largely regulated
by the individual States so an answer which is correct for one State
may not be correct in another. Many cities also may have regulations
and or statutes which may enter into the answer, which makes any
attempt at a universal answer exceedingly difficult. Now having
stated this I am of the lay opinion that in many jurisdictions Pawn
Shops, which operate under considerable legal supervision, may
legally sell items which they have purchased even IF these items
later prove to have been stolen, and the Pawn Shop was not aware of
the sellers inability to have transferred ownership.
I wrote a story on pawnshops for New York Diamonds magazine last
July. I would be happy to send it to anyone who writes to me. It
should answer many of your questions.
The jewelry involved in the shops I wrote about is generally
commercial but the process will be the same for handmade jewelry.