Is that 95/5 or 90/10 Pt? It can make a big difference. I have
found a coarse stone finish to outlast a fine grain sandblast,
ideally your customer will like that or a coarser sand blast as a
background for the wear every day patina that will be permanent. I'm
afraid a satin finish will not last any better than the sand blast.
You should hear the din from retailers whose clients had been told
platinum is harder than gold and expected the bright polish to last
for years with all day every day wear and tear!
Orchidians take note I get this a LOT. With rare heat treated
exceptions 95/5 is soft compared with white gold for impact
resistance and general scratch resistance. Alloys vary this is a
general rule only. I saw a Pt ring shank beat to death by a yellow
ring shank on a Sunday morning at a church. The handclapping that
went with the hymnals was just too much for the poor 95/5 shank up
against a 10kt yellow shank.