Pearl is the birthstone for the month of June. It is also the accepted anniversary gemstone for the 3rd and 30th years of marriage. A pearl is the product of an oyster's defense mechanism. When a foreign irritant is introduced either by man (cultured) or naturally, the oyster immediately surrounds it with layers of a substance called nacre. This forms the exquisite gemstone know as pearl. Pearls come in a wide range of colors. They should be relatively free from skin blemishes. The more perfectly round the shape the better. The higher the luster, or "orient", the more valuable the specimen. The larger the pearl, the greater the value. Besides the popular round shape, there are stylish mabe (large hemispherical cultured pearls), fresh water (elongated in interesting shapes and colors), and South Sea (large cultured pearls 10mm and up from Australia's and Indonesia's waters), to name a few. Pearls have been recognized as the emblem of modesty, chastity and purity. They have come to symbolize a happy marriage. Avoid household chemicals, cosmetics, hair sprays, and perfumes. Don't use ultrasonic cleaners. Wash with Original Diamond & Precious Jewelry Cleaner and store in a protective chamois pouch or tissue paper. Moonstone is sometimes used as an alternative by those born in June since it physically resembles some pearls.