I got outbid at very end. I thought it was a real coin made into a pocket watch key. Your thoughts?
While genuine ancient coins can and have been turned into modern jewellery items, I don't think this one was genuine. The qoppa beneath the pegasus looks definitely wrong (should look more like a Q) and the fields have a cast-like look to them.
It does look grainy like it was cast
I think this is modern and one of the reasons is that both sides of the piece are exquisitely centered.
Good point Tom.