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Alum to dissolve broken drill bit safe for stones?

I got a tiny bit of drill bit broken off in a tiny pilot hole I was
hand drilling. It’s stuck in there really hard. It’s only a little
fragment. Attempts to continue drilling in the hopes that it would
loosen means the drill is now working next to the broken bit. If I
continue the hole will be too large. The hole is too small to get
anything in thereto get a grip on the fragment.

This is a finished piece of jewelry, a customer’s repair, and I just
wanted to wire on a bail to replace a soldered one that broke off.
There is a stone only about 2 mm under where the hole was supposed
to come out. It is an open backed bezel set stone, stepped bezel,
set really high. Therefore there is room to fit a wire in, under the
rim, I “just” needed to be careful with drilling so I wouldn’t hit
the stone.

It was two bezel set citrines (or they might be lemon quartz, I
forget). So taking out the stones is not where I want to go. Is it
possible to use alum with faceted non-porous stones?

Brad Smith kindly suggested soaking it in alum and water to dissolve
the steel, but I don’t know if this is safe for stones. A google
search turned up one statement that it wasn’t. Is this true of all



I’ve tried alum to dissolve a broken bit. 4 days in a super saturated
solution, with no noticeable result. Simply didn’t work.

A fresh batch of pickle had the bit out in about 2 hours. Mix it a
little strong, use it hot, and you should be good. Mix new, so
there’s no copper in it to plate out.

Brian Meek

i have used various chemicals to dissolve broken drills and taps,
almost always with good results.

i have never soaked an entire pieces in a chemical, I always just
put some down the hole, wait a few minutes, and see if i need to
apply more.

I think doing it that way would be much easier than soaking.


Alum will not affect quartz so you can carry on.

Nick Royall

Try soaking it in a strong sparex pickle solution. That should do
the job.

Steve Arista designs llc.

It needs to be a concentrated solution of alum, I do not think it
will affected quartz (citrine). Do a test on an unset quarts if


I've tried alum to dissolve a broken bit. 4 days in a super
saturated solution, with no noticeable result. Simply didn't work. 

I use alum all the time to take out broken drill bits. Mix your
saturated solution in small (I use 30ml) beaker and pop it in the
microwave for about 20-30 seconds and let it sit overnight (and
sometimes two overnights)