The platinum hasn't gone anywhere, its harder to solubulize than gold. You would not have a finger left if something removed the Pt. Copper would turn blue green ( Copper sulfate) if acted upon by body acid, not uncommon. I take lots of Iodine
and wear .9 Pt .1 Pd combo with no color or weight change in years. Can't explain the Pt change unles it was only gold coated with Pt to begin with.