Customer Service

Certificates of Authentication, Valuation Certificates

All customers who purchase Glous jewelry will receive a Certificate of Authentication or a Valuation Certificate issued in Japan with their product. Glous’ Certificates of Authentication and Valuation Certificates are issued by one of the following authentication agencies.

*Click each Authentication and Valuation Certificate to enlarge.

Central Gem Laboratory

This laboratory is well-known for its expertise in authenticating and valuing diamonds, in particular. A high degree of specialized knowledge and experience is used to analyze different types of gemstones and differentiate between natural and imitation stones.

Pearl Institute Co., Ltd.

Established in 1998 as an authentication agency specializing in pearls. Issues the largest number of Certificates of Authentication for pearls in Japan. The company is also well known for the outstanding design of its authentication certificates.

Pearl Science Laboratory

A laboratory that’s widely recognized as a leading expert in pearl authentication. Pearls which have passed the quality test are issued a Quality Authentication Certificate that includes, for example, the Highest Quality Mark and the Outstanding Luster Mark.

Kiho Kagaku Kyoukai (Scientific Association for Jewelry)

A gemstone authentication agency located in Okachimachi, Japan’s only wholesale jewelry district, Kiho Kagaku Kyoukai authenticates a wide range of jewelry from coral to pearls.

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