How to Storing Black Pearls
Black Pearls are composed of about 2-4% water along with calcium carbonate and an organic binder called conchiolin.
If they become dehydrated, they get brittle and crack.
So, they should not be kept near heaters, or gettubg strong sunlight place.
Also sealed plastic bags are not the best place for them, please keep them from breathing and getting moisture.
Jewelry pouches, cloth bags or something to be wrapped in soft material are best idea.