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Polishing Coral & malachite


#1

Hello all you people out there in jewelry land! Does anyone know
how to polish red branch coral? It is in it’s natural state.Thank
you and wish I was going to Tucson! S.Bradley

I have always used triploi & rouge for polishing these stones.
Works fine for me. I understand that malachite is poisonous for
people that are polishing large quantities. I also clean these
stones in the ultrasonic cleaner and steam. If left in the
cleaner too long, they will come out dull. Coral is hard to clean
of rouge. The remedy here has been to rub the coral down with an
application of mineral oil after the ultrasonic has dulled the
finish. Took me about 25 years to find this solution.

Bruce D. Holmgrain
E-mail: Manmountaindense@Knight-Hub.com
WWW: http://www.knight-hub.com/manmtndense/bhh3.htm
Snail Mail: POB 7972, McLean, VA 22106


#2

Hello all you people out there in jewelry land! Does anyone know
how to polish red branch coral?

I also clean these  stones in the ultrasonic cleaner and steam. If left in the

cleaner too long, they will come out dull.

This comment and a couple of others could possibly be taken to
indicate it’s the ultrasonic sound waves that dull the finishes
of coral and malachite. Both materials are carbonates and the
finishes are damaged by acids that may be present in the
ultrasonic cleaning solution, not the ultrasonic waves (although
they are soft and could be damaged by abrasion with the metal of
the tank) . The reaction is similar to pouring vinegar onto
baking soda. Unless you want a repolishing job, keep these
materials away from all acids; also rhodochrosite, azurite and a
few others. Since lots of drusy minerals are now being used in
jewelry, be very sure you know what the minerals are before
dunking them into any acidic solution.

Rick Martin
MARTIN DESIGNS