Pearls are valued according to several factors.  Type- Pearls from the South Sea are the most valuable. Shape- Perfect roundness is the most popular and is the most expensive.  Sizing- The larger the Pearl, the more value it holds. Coloring- Dependant on the need, Pearls come in a large variety of natural colors.  Surface Quality- The smoother and more perfect the surface of the Pearl, the higher the cost. Luster- Pearls must have that Pearlescent luster inside, and the deeper the luster, the more value the Pearl has.