As with any porous stones I don’t ever put those in an ultrasonic in
the first place. The Oakite is pinkish in color.
Through my experience all metals don’t have a reaction with this
except silver. When we do silver objects it can tarnish it if you
leave it in there too long.
Generally just swish it in there with the sonic running, rinse and
steam and you are good to go. For porous stones just use a toothbrush
with the solution to clean and rinse immediately.
GIA uses this in their JMA classes and it is terrific.