It looks like a talisman,see if it's unidentified and take it Diane so she can tell you what it is,If I remember it's a Tipak something like that,I know starts with a T I think was name of tribe,you can't sell that item.Remember the scene where you went with Diane to that mountain,where she fell on top you,she said something down there and she pulled it out,then you showed it to the rich lady in her mansion.And another question are you using the cheat MOD?people been having issues with it,for me Margaret dissapear when I had do quest.If you need save files I'll attach them,they from different parts of game and if need game save editor let me know I'll send you link,better than the Mod