Routine Pearl Treatments
Large factories in Japan and China process pearls in bulk. Since these are the major producers of pearls, this results in uniform appearance and excellent matching for most pearl strands. After pre-treatment washing, most pearls undergo bleaching, dyeing, and a light polishing, and some types also receive luster enhancement. While many people view dyeing negatively, there’s little to no stigma associated with these routine pearl treatments.
Once out of the shell, pearls are tumbled in a mildly abrasive saltwater solution that removes stuck organic matter.
After this step, experts grade the pearls, which determines their subsequent level of treatment. Only top-quality pearls receive no further treatment. (For Akoya pearls, for example, these are Hanadama-quality pearls). Sellers may also advertise other cultured pearl types as untreated.
Maeshori Luster Enhancement
Most pearls undergo maeshori (Japanese for “before treatment”), a secretive luster enhancement process. This involves a hot and cold treatment, and the exact steps vary between factories. In fact, some factories even combine the heating process with bleaching chemicals.
Ultimately, maeshori tightens nacre layers, which drives water out of the pearl. Many liken this treatment to a “facelift” for the pearl.
While this results in…