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Jewelry, Gems, & Minerals/cleaning carved mother of pearl


I inherited some carved Bethlehem mother of pearl brooches from my grandmother.  My mother had it stored away in a box for many years.  Several of the pieces have a black residue on them, which looks like mildew.  I have tried to clean them with a very soft toothbrush and mild soap, and while the surface of the pieces now looks good, there is still black stuff in the intricate spaces that I can't remove.  Do you have any suggestions?  I know not to use acidic solvents or abrasives.  

Thank you!

Dear Kendall,

The generally most accepted cleanser for pearls and mother of pearl are a mild dish detergent and water. There should be no ammonia in the detergent. Cleaning is with a soak followed with brushing gently with fine and soft bristles with the solution. Rinse well and using a stronger water spray is often useful, as from a  "Water Pik" tooth and gum cleaning machine or sink sprayer.  When this does not remove residue, the material may not be something dissolved or easily dislodged with cleansers.  

I suggest the safest approach at that point is to have the brooches cleaned by a jeweler using an ultra sonic cleaning machine.  You must be sure the cleanser in the machine does not contain strong alkaline or ammonia components. If the solution is ammonia based, the brooch may be placed inside a zip-lock baggie with a dish detergent/water mix and that put sealed into the machine tank. The ultrasonic action will work right through the baggie with the detergent to help dislodge the material in fine creases. A couple of minutes is long enough. If that does not do it, the material may simply not be going to come off or out of the brooch.  Only put one brooch at a time in the baggie to prevent one from abrading the other.  Obviously, this cleaning would be at a jewelers and their may or may not be a charge for the service. At that point, you will have done about the best you can and the final stage of cleanliness is what you have.

Kendall, I do hope this info will be of use to you.  God Bless and Peace.  Thomas.  

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Have a question about jewelry repair or working with precious metal jewelry and gemstones? For many years up to December 31, 2010, I was a working professional bench jeweler, involved everyday with setting stones in mountings, designing and making jewelry, repairing and limited custom manufacture. If you work with jewelry as a hobby or as a profession, I might be able to help. I deal with the retail business, not mass production. Ask privately if you wish. See the box for that: It keeps your question between us. Please DO NOT ask MAKER'S MARKS, but metal quality marks are fine to ask. Please DO NOT ask diamond prices. See a gemologist for that.


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