While you are shopping for bright metal inlay for a sight leaf or for a front sight bead, consider the distinct possibility that the bright metal that is or was there is Fine Silver, basically pure (not alloyed) silver.
Fine Silver (unlike Sterling Silver) doesn't tarnish, and it is far more ductile than platinum and it takes a very bright polish. Also if it needs to be brazed (silver soldered - high temperature), for instance a bead on to a front sight blade, the metalsmith will be using silver alloy as a filler metal to make the joint. Brazing platinum is tricky and the material is susceptible to contamination in the brazing process.
