On a scale of 1 to 10, pearls are classified as 3 on the 'Mohs' scale of hardness, whereas diamonds rate as 10, being the hardest mineral in existence. Compared to a diamond, the pearl is therefore relatively soft and can be scratched by a gemstone. Ideally, pearls should be stored separately in a soft pouch. Pearls are made of calcium carbonate with an outer covering of aragonite. They are sensitive to acids and other corrosive substances, so should never be exposed to household substances, perfumes, or other acidic materials. Pearls should always be removed when swimming in a chlorinated pool.
Pearls can fade and crack if exposed to extreme heat, or kept for years in a dry atmosphere such as in a safe.
Tahitian pearls require relatively little care. They ask only to be worn from time to time so that they can be hydrated by direct contact with the skin. Simply wipe pearls with a soft cloth to preserve their beauty and gloss, or alternatively wash them in clean seawater.