My feelings as a coin collector causes me to wince when I see this
being done. I suggest you take a mold of the coin. Cut out the wax.
Cast a new positive, then cast as many as you like with a new mold.
“Authenticity” is irrelevant when the coin is destroyed.
Artistically, I see little in it. Better to use a frame.
Handcrafted Celtic and Medieval Jewelry
in Sterling and Gold