Mm Size: Most of the size of the black pearl of Tahiti between nine and 12. Millimeters rare and more valuable the black pearl size between 12 and 18. Now, could only ask the person showing the pearls for your micrometer to know exactly how big is the black pearl you are viewing.
Form: There are five categories of forms of black pearl.
Round: a perfectly round ball
Semi-round: slightly imperfect in form
Semi-baroque, pear-shaped, teardrop, oval or button
Baroque: irregular shaped non-symmetry
Circle: characteristic bands around the black pearl
Quality: This is a difficult category. Look for surface imperfections and highlights, a bright and sparkling, and the ability to reflect light. Quality of surface divided into four sub-categories:
* A - one or more visible imperfections on less than 10 percent of the area, with notable Luster.
* B - visible imperfections on less than 33 percent of the surface, with a reasonable brightness or scheduled.
* C - visible imperfections less than two thirds of the surface with regular brightness.
* D - visible imperfections on more than two thirds of the surface with a dull glow.
Natural Color: black pearl come in various colors. The most common is black or gray. Color tone may come in shades of blue as the moon, silver, gold, gray, pink, the colors of the most valuable comes in shades of peacock green, eggplant and rainbow.
