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Cutting black star sapphire crystal

I have a black star sapphire crystal and I was wondering if there
was some on cutting it. I have a little lapidary
experience. Thank you

To find and orient the star in your saphire crystal you can lightly
dome both ends of the crystal, sanding up to 600 grit. Then use
liberal amounts of a light oil like “Crystalite’s crystal lube” or
3-M’s sewing machine oil on the domed ends. You will be able to see
the chatoyance in the crystal then. The reason you dome both ends
is because usually one end of the crystal will have a stronger
chatoyance than the other. Now that you have established which end
has the strongest star you can dop the stone with the best end out.

Now is the tricky part. It helps to dim room lights if possible and
have a source of light that you can look down like a pen light or
small flashlight. It is extremely important that you be looking
from the same direction as the source of your light. You need to
orient the “star”,which will just be a spot of chatoyance at this
point, in the middle of the stone. It helps if you have your burner
lite and can warm your dop wax occasionally so you can move the
stone. Sighting down the penlight slowly turn the dop in your
fingers and watch the chatoyant spot on the crystal. When you have
it properly oriented on the dop stick it will remain in the center
throughout 360 degrees of rotation of the dop.

Now that you have the crystal oriented on the dop stick you can cut
it on a trim saw at 90 degrees to the dop, any and all pieces you
cut from this crystal now will be oriented so the star will be
centered. It is helpful, if the crystal is large enough for several
stones, to mark the top of each slice in some manner, i.e. with
aluminum marking pencil or permanent marker, for future reference.

Good luck, I hope this was of some help. Dean Welter

Dean, For the sake of accuracy, star gems do not exhibit chatoyancy.
The phenomenon in a star stone is asterism. Chatoyancy is what causes
the “eye” in catseyes. Jerry in Kodiak