Wear them!!! Wear them at least semi-often!! Pearls were originally born in the water and benefit immensely from absorbing the oils that your skin naturally secretes throughout the day. So go ahead, put them on and show them you care.
Gently wipe your pearls with a soft cloth to remove sweat, perfume, excess oils or dirt before putting them away. Be sure to put your pearls on after dressing up.
Pearls should be stored properly from other objects or jewelry that may scratch the nacre. Wrap your pearls in linen, soft cloth, or place in a soft pouch.
Do NOT store pearls in an airtight package such as a plastic bag: pearls need moisture. If the environment is too dry, the pearls may crack. If placing the pearls in a safety deposit box or in a hot environment, leave a damp cloth nearby, and try to get them out of there as quickly as you can.
Remove pearls before exercising to keep them away from perspiration.
Do not submerge your pearls in water - no showers, no dishes, no swimming. The chlorine in the water will eat away at the epoxy securing the pearls to their mountings, and soaking the silk your pearls are strung on causes it to stretch out and break early.
Avoid hanging the pearl necklace for on a hook for storage; this places un-necessary strain on the silk and stretches out the necklace.
Restring pearls once every two to three years, or once a year if you wear them weekly. Be sure to have each pearl knotted separately, preferably with silk or pearl bumpers so they will not rub together.