"Who comes with summer to this earth
And owes to June her hour of birth
A pearl should wear against her skin
Who's innocence many a heart should win"
The word Pearl is derived from the Latin word "pirum", which means "pear". The pearl has a smooth lustrous round structure having a brilliant luster, with varying tints, and is found inside the shell of a mollusk such as a clam or oyster. It is formed due to a secretion of shelly substance around some irritating foreign particle. Its substance is the same as nacre, or mother of pearl. Pearls which are round or nearly round and have a fine luster, are highly esteemed jewels and compare in value with precious stones. Real pearls are made by oysters or other mollusks, whilst imitation pearls are man made. Cultured pearls are made by mollusks, but with human intervention. A good sized pearl can take between five to eight years to form, which is usually the entire life of the oyster or mollusk. The cost depends on the size and the coating, or nacre, on a real pearl which gives it is iridescence.