How to classify Tahitian Pearls
THE SHAPE
Round: an almost perfect sphere with a maximum 2% variation in diameter. These are the rarest and most expensive pearls.
Semi-round (near-round): a spherical pearl with a diameter variation between 2% and 5%. Once mounted, they appear round but are more affordable.
Semi-baroque: drop, pear, oval, or button-shaped pearls. The diameter varies by more than 5% but they retain an axis of symmetry and are often used for pendants.
Baroque: irregular pearls with no definite shape or axis of symmetry; they do not fit the categories above.
Circled: pearls having one or more concentric rings.
THE SURFACE QUALITY
The criteria for surface quality combine two characteristics: the condition of the surface and its luster. This is assessed with the naked eye.
Surface condition can show various imperfections such as pits, scratches, striations, creases, grooves, depressions, dimples, organic deposits, bumps, blisters, growths, or milky depigmented spots.
Luster (shine/brilliance) refers to how perfectly light is reflected on the pearl’s surface. It depends on the regularity, thickness, and arrangement of the nacre layers.
A very fine luster gives a mirror-like effect. A pearl without luster appears dull.
Standardization of surface quality for cultured Tahitian pearls:
Grade A: at most one imperfection, or a group of slight imperfections, concentrated on ≤ 10% of the surface. Very fine luster.
Grade B: slight imperfections concentrated on ≤ 30% of the surface. Luster: very good to medium.
Grade C: slight imperfections concentrated on ≤ 60% of the surface. Luster: very good to medium.
Grade D: either slight imperfections over > 60% of the surface (with no deep imperfections), or a mix of slight and deep imperfections concentrated on ≤ 60%. Luster: very good, good, medium, or low.
The plus sign (+) indicates a pearl with a very fine color and exceptional luster/shine.
Because each pearl is unique, the jeweler’s job is to mask any flaws: cover them with the setting (Cat. A) and place them on the hidden side when worn (Cat. B & C). Only Grade D pearls may show visible flaws on the front of the jewel.
THE SIZE
In addition to their color, size distinguishes Tahitian pearls from white Asian pearls.
Size is measured by diameter (at the widest part for semi-baroque pearls).
The smallest have a diameter of 8 mm. Medium sizes are around 11.5 mm.
Pearls larger than 12 mm are rarer and represent a small share of the harvest.
Pearls over 14 mm are exceptional; those of higher quality are especially sought after.
THE COLOR
The commercial name can be misleading: “Black Tahitian pearls” are not all black.
Colors range from pure white to deep black, through every shade of silver-grey, peacock green, eggplant, blue, golden brown, and even rainbow overtones.
These colors are natural and vary according to the donor mantle (graft) inserted with the nucleus, as well as farming practices and the lagoon.
Color is not a quality criterion; each person may choose according to personal taste.
For accuracy I use a color chart to determine the precise color of each pearl. The letter (c, r, or e) after the color indicates rarity: c = classic, r = rare, e = exceptional.
EXAMPLE OF COMPLETE DESCRIPTION OF A PEARL
Shape
Grade
Size in mm
Color
Color rarity
