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Polishing Petrified Coral


#1

Hello,

Can anyone suggest how to get a shiny finish on a piece of black
petrified coral I have cut and shaped? Do I need a horizontal tin
lap with a paste or can I do it on a Pixie?

Thank you
Sheridan in Chicago


#2

Sheridan,

I have cut and polished many pieces of petrified coral…black,
red, brown, white…you name it!

Originally, the coral was simple calcium carbonate and would have
been difficult or impossible to “polish”. However, the petrified
coral (especially the kind from various parts of Florida…is that
yours?) has become agatized and thus is silicafied. Silica polished
best with cerium Oxide paste on felt…primarily soft felt. I
don’t know how you have ’ cut and shaped it’ but would suggest you
find some soft felt wheelsd that will fit the form of your shape,
make up a paste to apply to the felt and keep it slightly damp as you
turn it slowly against the surface. If it is a large flat surface,
you can either rub it by hand or use a felt surface on a flat
lap…and end plate is very handy for this. Be sure the surface is
prepared to a pre-polished state before trying to polish it!Q

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