Size: When the size is big, the pearl is more valuable. Pearls with a 7mm or low diameter are called beads and those with a higher diameter than 8mm are called gems.
Surface: The quality of the surface is an important factor in determining value.
Shape: Perfectly round pearls are most valuable, there are drops, circles, baroques and rounds, and some special pearls come with special colors that are different from the standard colors. They are rare.
Color: The color of pearls affects the value of the pearl. Natural colors are white, pink, peach, purple, gold, metallic, silver, gray, and black.
Nacre: Nacre thickness is a characteristic applied to measure the value of the pearl. Pearl luster is the shine and glow and the light reflected on the surface of the pearl.