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Drilling lengthwise into a polished rock

Hello - I’m a hobbyist beader who prefers but also work in
glass. My dilemma lies in my love affair with agates and jasper. I
have some great polished rocks that I would love to have a
lengthwise hold drilled ALL THE WAY THROUGH the center so I could
make a focal bead out of it. Now, I’ve become very aware that if
you want to clear out a room of lapidary people at a party, just
asked, "how do I drill a hole lengthwise through a polished rock."
I know it must take a diamond bit and a lot of persistance, but I
know it can be done because I’ve purchased many gemstone beads with
holes in them. So, I would really appreciate someone offering up
the “secret process” that seems to strike fear into the hearts of
other rockhounds. Remember, your responding to an individual that
has trouble negotiating the proper placement of a nail in a wall for
adequate picture hanging. Thanks in advance.


there are a couple of ways to do this:

  1. for small beads and pearls, using a japanese style pearl drill 2)
    using a bead holding jig

in the case where you are drilling the long axis of a stone, where
the ratio of the long axis to the width is anything grater than
about 1.3:1, then what i do is drill the hole first, then use the
hole as the reference point to carve the rest of the stone to.

finding the center of a circle is not always so easy to do when the
circle has a somewhat irregular shape; also, drilling on exact
center is not always so easy to do, as the hole tends to drift off
center; that is why i like the approach above.

Also, i am most likely to loose a piece (trash it) when I am
drilling the hole, either through bad hole placement, or a fracture
developing. if so, then I want this to happen early, before I then
put 40 hours or more carving the rest.


I don’t know who these lapidarys are who are afraid of drilling a
hole that you talk about but I suspect they don’t have a very broad
knowledge of the lapidary process. In fact, the way to drill long
holes into stones such as those used for stringing is to use an
ultrasound drill. Such drills have been around for years and are
capable of drilling even very small holes through long thin stones.
For short holes, common diamond drills used in a drill press or even
a flex shaft will do the trick. One problem with the ultrasound
machines is they are fairly expensive. I don’t have one so cannot
give you a price range but lets just say, its not worth buying one
for a hole or two! This question comes up often and there must be
more in the Orchid archives on the subject!

Cheers from Don at The Charles Belle Studio in SOFL where simple
elegance IS fine jewelry! @coralnut2