From my own experience I would be suspicious !
Obviously someone has made at least one jewelry piece in the pic.
Twenty years ago while experimenting with casting techniques I realized how simple it was to produce uniface castings of some of my favorite coins. On one small 18mm Ptolemy AE I made a gold uniface casting and soldered a small loop to it. I made uniface castings of several pieces and kept them to use for another project later on which never developed.
If I woke up 'dead' tomorrow my widow might find a similar number of items and take a single picture that would look very intriguing ! Most would be real of course but she would at some point find the castings too.
But being
ebay it is possible that they are real or fake or an 'interesting' mix of both !
Nothing ventured
Nothing gained