Lapidarists
I’m working on an inlay malachite piece in sterling bezel. Due to the
complexity of the design I pre cut the malachite to fit exactly into
the bezel so I just needed to give a quick buff after epoxy. I used a
small felt wheel on the Fordham with liquid spray (not paste) 50k
mesh diamond spray to top off the stones and a black spot appeared. I
went to wheel #6 (finest) on the polisher to gently grind off the
spot using light pressure, fairly short intervals of contact on the
wheel with plenty of water spraying. I seemed to be making progress
when another black spot appeared then a pit formed and the disaster
was complete. I nicked the neighboring stone in the process, which
was why I didn’t want to have to top off the stones in the first
place and gently (really - I was not pushing it after what just
happened) ran it on #6 and a black spot developed on the second stone
which then cracked and pitted. I’ve polished malachite before and
never had this problem. I’ve ground out the stones and am re-cutting.
I know malachite can be brittle but what just happened? Of course it
was the final clean up before photography. I’m too devastated and
dazed to even cuss.