I bought it for scrap value. I paid a whole $3 for it. It's 14K.
I was thinking a tie tack at first, but then I thought maybe it is a removable button? It's mother of pearl I think with a pearl in it .The back of the square piece is also all gold. Did not test it yet.
If its not out of the way.. It may be a button too, not sure of the exact name of it. But it would go in the top couple buttons for a dress shirt. But it would depend on the size of it. So there could be 1 more there could be 3 more.