Hello Calgang, Decades ago my husband bought me a strand of Mikimoto
pearls in Hong Kong. The with them advocated cleaning
the strand by gently rubbing each pearl with cotton dampened (not
dripping) with a 50-50 solution of warm water and rubbing alcohol.
That’s what I’ve been doing for lo these many years, and the pearls
continue to have wonderful luster without build-up. I’ve seen other
methods, but this one has been successful for me.
Judy in Kansas where it’s cold and dreary today