Phil Burns asked if I could let him know the age/period of this find. It’s a copper-alloy seal matrix, which has an intaglio set into the base.
The intaglio is probably glass, which has two classical figures cut into it. As can be seen from the illustration, it produces a very good impression. The copper-alloy body would probably have had a suspension loop at the top but it has been lost.
I’d suggest this find would have been made during the Georgian period and I would date it to circa 1750-80. It would not be of much commercial value but it is nonetheless an interesting detecting find.