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Polishing Garnet cabochons


#1

Hello Gini, The biggest problem with garnet is the heat build up
and subsequent cracking that will occur. Avoiding thermal shock
is simple…patience, and touch the stone at all times or at
least frequently during polishing. Felt wheels may restore the
polish but cause a very rapid heat build up so extreme caution is
to be taken, if the stone is small try this;

Take a wooden golf tee and chuck it in your flex shaft mix 8,000
grit diamond with lipstick, vaseline or floor wax and prepolish
the stone being held with the cup of the tee. Another tee with
50,000 diamond will put a sparkling polish on your stone. This
also works extremely well with tiny sapphire and ruby cabs and
they don’t have to be dismounted to polish. I can’t seem to
control the tee on stones over 6-7 mm but then I have proper
lapidary equipment for stones big enough to hang on to.

This is a fairly rapid process once you have these tees prepared
and are very handy for putting a great polish on small cabs on
pieces taken in for repair. I have a selection of tees carved and
cupped to different profiles which I keep in 35mm film plastic
containers. It is better to have the cup smaller than the stone
allowing the tee to roll over the entire surface exposing all
parts of the stone to all parts of the rotating cup, this makes
sure you have a uniform polish.

I always buy loose diamond and make my own paste which gives me
control over the aggressiveness of the mix. Commercial pastes are
invariably too frugal for my impatience. I can buy retail
guaranteed synthetic for less than $5 CDN per ct do NOT buy
natural diamond boart no matter how cheap it is. A carat will
earn you many times its cost, it will be enough to recharge a tee
cup at least a dozen times and a tee will polish many stones
between recharges. Your local rock shop will have the diamonds
and a golfer shouldn’t be too hard to find.

HTH…Tony.