The B grade is the second tier in the official Tahitian pearl grading system administered by the French Polynesian government under regulations governing the export of cultured pearls from Pinctada margaritifera. A B-grade pearl may carry surface imperfections covering up to 30 per cent of its total surface area, and those blemishes may be concentrated in a single zone rather than distributed evenly — a meaningful distinction from the stricter A grade, which requires imperfections to be minor and largely confined to one small area. Despite this latitude, B-grade pearls must still exhibit acceptable lustre and meet the mandatory minimum nacre thickness of 0.8 mm, the baseline threshold applied across all exportable grades.

Regulatory Context

French Polynesia introduced formal pearl grading legislation to protect the international reputation of Tahitian cultured pearls and to provide buyers with a standardised, enforceable quality framework. Under this system, pearls are assessed before export and assigned a grade — A, B, C, or D — that must appear on official export documentation. Pearls that fall below the D threshold, or that fail the nacre-thickness requirement entirely, are prohibited from export. The B grade therefore occupies a clearly defined middle position: it acknowledges visible surface character while guaranteeing that the pearl possesses a commercially viable nacre layer and a degree of orient and lustre consistent with the Tahitian pearl's market identity.

Surface Characteristics

The permissible imperfections on a B-grade pearl include the range of surface features common to cultured pearls: minor pits, scratches, welts, rings, and chalky or dull patches. The critical regulatory point is the 30 per cent ceiling — no more than roughly one third of the pearl's surface may be affected. Because the regulations permit concentration of those blemishes, a B-grade pearl may present one hemisphere that is largely clean and lustrous while the opposite side carries the bulk of its surface marks. This characteristic makes B-grade material particularly practical for certain jewellery applications, such as pendants or earrings, where one face of the pearl is prominently displayed and the reverse is obscured by a setting or mounting.

Lustre and Nacre

Lustre in Tahitian pearls arises from the interaction of light with successive aragonite platelet layers within the nacre. The 0.8 mm minimum nacre thickness required of B-grade pearls is the same floor applied to A-grade material, ensuring that even the more commercially accessible grades retain the depth of lustre and the characteristic iridescent overtones — green, peacock, aubergine, and silver — that distinguish Pinctada margaritifera pearls from other cultured pearl types. A pearl with nacre thinner than 0.8 mm is ineligible for any export grade and cannot legally enter international trade channels from French Polynesia.

Commercial Significance

B-grade pearls constitute a substantial share of total Tahitian pearl export volume. Their price point sits meaningfully below A-grade material, making them accessible to a broader range of jewellery manufacturers and wholesale buyers. For designers working with multi-pearl pieces — strands, pavé-set clusters, or fashion jewellery — the B grade offers a route to authentic Tahitian pearls at a cost that permits creative flexibility. The grade designation on export paperwork also provides buyers with a documented quality reference, reducing ambiguity in wholesale transactions and supporting consistent pricing across markets.

Further Reading

• GIA: Pearl Quality Factors — gia.edu