T/SZS 4039-2025 The quality evaluation of sea pearls

Scope

Scope: This document specifies the quality factors and grades of seawater pearls, the grading of seawater pearls, sampling inspection, evaluation methods, and requirements for evaluators, etc. This document applies to the trade of bulk seawater pearls and quality evaluation activities related to import and export auctions. It does not apply to seawater pearls that have undergone treatments such as irradiation and dyeing, or composite seawater pearls. Main technical content: 5. Seawater pearl grades 5.1 Grading of seawater pearls According to comprehensive quality factors such as shape, luster, and smoothness, seawater pearls are evaluated and graded into four levels: Excellent, Very Good, Good, and General. 5.2 Grading of seawater pearls 5.2.1 Minimum requirements for Excellent-grade seawater pearls 5.2.1.1 Shape level: Round (A). 5.2.1.2 Luster level: Extra Strong (A). 5.2.1.3 Smoothness level: Very Good (B). 5.2.2 Minimum requirements for Very Good-grade seawater pearls 5.2.2.1 Shape level: Elliptical (B). 5.2.2.2 Luster level: Strong (B). 5.2.2.3 Smoothness level: Good (C). 5.2.3 Minimum requirements for Good-grade seawater pearls 5.2.3.1 Shape level: Flat-round (C). 5.2.3.2 Luster level: Medium (C). 5.2.3.3 Smoothness level: Medium (D). 6. Evaluation methods The evaluation methods specified in GB/T 18781-2023 are used to evaluate the shape, luster, and smoothness of pearls. 7. Sampling inspection 7.1 Sampling method Each batch of seawater pearls is treated as an independent lot, and the whole-group sampling method is used. 7.2 Sampling steps 7.2.1 Evenly spread the seawater pearls of the same batch on a tray. 7.2.2 Use a special partition board to divide the seawater pearls into several non-overlapping parts, each of which is a group. 7.2.3 Determine the number of groups based on the sample size. 7.2.4 Randomly select one group from the total groups as the evaluation sample. 7.3 Sampling requirements

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