Corroded Pearls

by SSEF, first published in Facette 20 (January 2013)

Although pearls, as organic gems, are commonly less stable than polished gemstones, we don’t often see pearls with obvious features of surface damage as a result of unfortunate care.

A few months ago, however, we received for testing a very spectacular case of such damage. The item was a pearl tiara, containing numerous natural and cultured pearls with heavily corroded surfaces. Based on the position of these corroded pearls on the tiara, the best explanation is that this damage was the result of careless use of hairspray, most probably used to fix the tiara on an extravagant hairstyle.

A close-up of the effects of corrosion on these pearls.

Especially the propellant gas found in such sprays may be very effective in dissolving calcium carbonate. Unfortunately, due to the careless and excessive use of such a hairspray, the said pearls have now lost considerable lustre and surface smoothness, and thus also value.