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Grinding star garnets


#1

Hi,

I’ve dopped a few of the 8 millimeter diameter garnets that I set
aside for practice and am attempting to grind cabochons on my flat
lap.

I’ve used a 175 steel diamond wheel, a 350 steel diamond wheel, a 325
foam backed 3M diamond paper wheel, and a 600 foam backed 3M diamond
paper wheels.

The foam backed wheels work great for removing facets.

I haven’t seen any asterisms though. At what grit or polish level
should I be able to see them?

Also, even if no asterisms are found, can they legitimate be used as
plain garnets?

Andrew Jonathan Fine


#2

If there is no star, then there is no star. Additional cutting will
not generate a star. Since you started with a garnet, you still have
a garnet.

John


#3

If your pre-polish is good enough, you may be able to see asterism
under a bright point light source if the garnet is wet, and if the
stone is oriented properly. If no star is visible, proceed to a
polish and check again. Garnet asterism is usually weaker than what
one sees in star sapphire.

Yes, the finished cab is still garnet and can be sold or used as
such, but will probably be very dark.

Good luck.
Dick Davies