Sorry not a dug find....but has aroused my curiosity. Any info on this would be appreciated....it's about the size of a quarter; it has some lettering on the inside...4 or 5 letters before the word co. that I can't make out; then below that 1/20th 12kt on Sterling...this is all in the same area under the hinge in the pin. Looks like it could be worn as a necklace or brooch. Thank you