Comparing DANAT’s Natural-Pearl Standards to Diamonds’ 4Cs
While the diamond world uses the 4Cs — color, clarity, cut and carat weight — to determine a stone’s value, the desirability of natural pearls rests on a different set of factors: weight, surface condition, shape, color, and matching (for pearl pairs or graduated strands).
These five criteria form the basis of the natural nacreous pearl grading system at the Bahrain Institute for Pearls and Gemstones (DANAT).
Surface condition is comparable to diamond clarity. Just as diamonds with better clarity tend to be more valuable, natural pearls with better surface condition and fewer visible blemishes will get a higher grade than those with blemished surfaces.
The symmetry of a natural pearl’s shape is an important value factor as well. Pearls with symmetrical shapes such as round, button, drop or oval will always be more desirable than those with asymmetrical or organic shapes. The comparable factor in diamond grading is cut, which determines the way a diamond’s facets interact with light. A diamond with high-quality polish, symmetry and proportions will exhibit brilliance, fire and scintillation.
In the color category, nacreous natural pearls that are lighter in color, such as white or light cream, are more desirable and receive higher grades than other colors. For diamonds, color grading is more nuanced. Among colorless diamonds, the lighter or whiter a stone is, the higher its grade. However, with fancy-colored diamonds, more intense hues garner higher prices.