~~~ field of the pearl chip/plaque was ground down in order to engrave it with whatever. I have quite a few pearls from there and have placed examples where you can still see the "F" and in some cases after being taken down the new engraving was upside down in relation to original serisl number.. and in many cases the reworked chips had serial numbets removed completely. Lots of this material made it up to Cuba as well... but where used is not my department.