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How To Drill Through Stones


I have an odd shaped obsidian, some pieces of marble, and several
fossilized casts from inside spiral shaped shells. I’d like to drill
through these to attach by wire or rods rather than create bezel and
prong settings for. Is there any tips or best drill bits to use so
that I don’t end up with dust!



Tee, Use a small diamond bit with water. If you know someone with an
ultrasound drill that works the best and the fastest. Joe

Expressions With Metal


tee - you will need at least one ‘diamond burr’: a drill bit that is
either ‘plated’ with diamond particles, or is ‘sintered’, where the
particles are incorporated/forged into the metal of the burr. there
are ‘core drills’ from 3/4mm to 2.5mm dia. from about $3.00 up - the
easiest ‘starter’ method is to find a metal jar lid about 1/2" bigger
around & as deep as the thickness of the piece you want to drill. if
you’ve got some rubber washers, superglue 3 onto the inside of lid -
no washers? just use something like thin pieces of cork - the object
is to raise the stone off of the bottom to let water underneath while
drilling. some people adhere the piece to the container, but i like
to just hold it & gauge the temperature of the water by feel. your
concern is not for the temp of the stone (usually stone temp is only
important when drilling material such as opals - which i do a lot
of), but as an indicator of the temp of the metal burr, burrs & bits
break more from high temp usage than from hard materials. DO NOT
check the burr with a fingertip! dip it in the water occasionally.
you’ve marked the spot for the hole with a sharpie (whatever) pen,
you’ve got your burr in whatever drill you’re using - flexshaft,
dremel, etc. you’ve got the piece in the lid with water covering it.
tap the turning burr onto the spot - by tapping instead of putting
the burr on the piece & turning on the drill you have more control &
the burr is less likely to skitter across the surface. keep tapping
for a second or two on the piece each time. when you’ve made a 'dent’
in the piece with the burr don’t start drilling longer than a second
or 2 & check the water temp. when you have drilled almost all the way
through, turn over piece, hold up to light & make a dot with the pen
where you see the light spot. tap through the rest of way. clean up
the hole by gently running the burr through it. you could smoothe it
more with an emery cloth, etc. use the emery on the glossy
chips/spots on the obsidian - it’s volcanic glass & as such, it chips
just like glass. that’s a simplified version that should see you
through the hole job - just remember that if you invest a little more
in a sintered burr or drill you will have it around for other stones
you like. good luck - ive


All the stones you describe can be drilled with diamond bits -
commonly available from any good lapidary supply house. These bits
must be used in a true running drill press and the contact point kept
under water - build a clay (‘silly putty?’) dam round the hole. the bit
must just touch the stone with very little pressure and be raised and
lowered avaery second or so - time consuming but satisfyingly rythmic.
The alternative is an ultrasonic drill - very quick but very
expensive. With either method if drilling clear through the stone
cater for breakout on the back by clamping something on the back or
reversing the stone and have 2 holes meet in the middle - needsa jig
or some luck.

Andy Parker, Agate House Lapidary
Ulverston, Cumbria, England
Tel: 01229 584023


Ive, Thought your explanation of drilling stones was clear, and
concise. Thank you. We only differ in how to hold the stone. Instead
of holding it only with my hand I submerge the stone halfway in
clean, soft wax (paraffin) which I premelt over a double boiler (to
avoid explosions). Helene