How to tell if a pearl is 'real'

To tell if a pearl is real, get the pearls wet (rinse under tap water) then gently rub a pearl against your front teeth. If the pearl feels slightly gritty, they are real. If it feels perfectly smooth, it is likely they are fabricated (glass with a coating, usually). Many pearls are grown by putting a small object inside of the oyster(salt water pearls) or mollusk fresh water pearls) - they are still 'real' - but the nacre is only coating the object rather than being pearl all the way through. In the case of coin pearls, for example, the object can be quite large - but the coating on the pearl is still formed by a natural process.