The D grade is the lowest quality classification permitted for export under the official French Polynesian pearl grading regulations, which are administered by Groupement des Producteurs de Perles de Tahiti (GIE Perles de Tahiti) and enforced by the territorial government. A Tahitian cultured pearl assigned this grade exhibits surface imperfections covering more than 60 per cent of its total surface area, yet still meets the mandatory minimum nacre thickness required for legal export — typically a minimum of 0.8 mm of nacre over the nucleus, as stipulated by French Polynesian law. Pearls that fail even this threshold may not be exported at all and are destroyed or returned to producers.

Surface Characteristics

D-grade pearls are distinguished by the extent and severity of their surface features. Acceptable imperfections at this tier may include deep pitting, pronounced ridges, calcification deposits, irregular or uneven surfaces, and areas of notably poor or absent lustre. Unlike the minor blemishes tolerated in higher grades — where imperfections are few, shallow, or easily concealed — the flaws on a D-grade pearl are pervasive and often structurally significant. The nacre may appear dull, chalky, or uneven in reflectivity across large portions of the surface. Baroque and semi-baroque shapes are common at this grade, though round and near-round D-grade pearls do exist.

Position Within the Grading Scale

French Polynesian regulations establish a four-tier grading hierarchy: A (finest), B, C, and D. Each ascending letter grade reflects a progressively greater proportion of surface imperfection and a corresponding decline in lustre and surface integrity. The A grade permits only minor imperfections covering no more than 10 per cent of the surface; the B grade allows up to 30 per cent; the C grade up to 60 per cent; and the D grade encompasses anything beyond that threshold that still meets nacre requirements. This system is mandatory — pearls must be graded before export, and the grade must be disclosed in commercial documentation.

Commercial Applications

Because of their pronounced surface irregularities, D-grade pearls are most commonly directed toward applications where the majority of the pearl's surface will be concealed or is of secondary concern. Typical uses include:

• Fully drilled beads in multi-strand necklaces, where drilling removes or obscures the most heavily blemished areas
• Budget jewellery lines where price point takes precedence over surface quality
• Craft and decorative applications outside fine jewellery
• Wholesale lots sold for processing or re-working

In the trade, D-grade material commands significantly lower prices than A, B, or C grades, and is rarely presented in fine jewellery retail without explicit disclosure of its grade. Reputable pearl dealers and gemmological laboratories will note the grade on any accompanying documentation.

Regulatory Context

The French Polynesian grading system exists to protect the international reputation of Tahitian cultured pearls, which are produced exclusively from the black-lipped oyster Pinctada margaritifera var. cumingi in the lagoons of French Polynesia. The export regulations, first formalised in the 1990s and subsequently refined, prohibit the export of any pearl — regardless of grade — that does not meet minimum nacre thickness standards. This means that even D-grade pearls represent a baseline of structural integrity; they are flawed in surface quality but are not thin-nacred impostors. The system as a whole is designed to prevent the market flooding that damaged the reputation of other cultured pearl origins in earlier decades.