Unfortunately, 950 iridio platinum won’t harden up all that
much. It’s not an alloy you can heat treat. Work hardening is
the only way, and with an already cast piece, this is difficult.
You can hammer it and bend it around, straighten it again, etc.
This will help. But you won’t get really hard out of it, only
perhaps some improvement. And unfortunately too, doing all this
will then require refinishing most likely, which will then
further thin the shank at least a little bit…
You might consider, if you can do so cleanly, putting on a new,
heavier shank. This time, forge it from 900 iridio platinum,
which is a bit harder, and using forged/rolled metal will help a
GREAT deal too.
he other option, maybe the most practical, is to just straighten
it. If She bends it again, you’ll straighten it again. After a
few cycles through this, it won’t be so soft… Not the best
public relations, though. but platinum being as it is, if the
metal is sound, she’s not likely to actually break the thing.
One note: After you straighten it, spend some time with a
burnisher, burnishing the surface good and bright again, instead
of sanding or emerying out any marks left. This is more work,
but you can smooth the shank again this way with almost no metal
loss, and the result will also be a somewhat tougher, harder
surface skin on the metal that will also help it to resist
future bending. Not completely, but it will help.