{"id":4520,"date":"2026-10-07T11:15:42","date_gmt":"2026-10-07T11:15:42","guid":{"rendered":"https:\/\/gems2u4ever.com\/?p=4520"},"modified":"2026-10-07T11:15:42","modified_gmt":"2026-10-07T11:15:42","slug":"lire-certificat-gia-lotus-saphir","status":"publish","type":"post","link":"https:\/\/gems2u4ever.com\/en\/lire-certificat-gia-lotus-saphir\/","title":{"rendered":"Comment lire un certificat GIA ou Lotus pour un saphir ?"},"content":{"rendered":"
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A gemological report is one of the most useful documents when buying an important sapphire. The key is understanding what it actually confirms.<\/p>\n

For the complete buying framework, read our guide to choosing a natural sapphire<\/a>.<\/p>\n

Often called a \u201ccertificate\u201d in the trade, it records a laboratory's examination and conclusions. It is not a guarantee of beauty, a valuation or an assurance that the seller's photograph matches the stone in your hands.<\/p>\n

Identification<\/h2>\n

Start with the identification of the material. For a natural sapphire, the report should identify natural corundum and the sapphire variety according to the laboratory's format.<\/p>\n

Read the full result. Do not confuse natural origin with an absence of treatment.<\/p>\n

Carat weight and measurements<\/h2>\n

Weight is given in carats; one carat is 0.20 gram. Weight alone says little about quality.<\/p>\n

Measurements are given in millimetres. They help compare stones of similar weight: a deep sapphire may weigh more without appearing larger face-up.<\/p>\n

Check that the reported dimensions and weight are consistent with the stone offered. Mounted stones can impose limitations on what a laboratory can measure or conclude.<\/p>\n

Shape and cutting style<\/h2>\n

The report may describe an oval, cushion, pear or round shape and the cutting style of its crown and pavilion.<\/p>\n

This description is not necessarily a cut-quality grade. You still need to examine symmetry, brightness, windowing and proportions.<\/p>\n

Treatment: respect the exact wording<\/h2>\n

The laboratory may record evidence of heating or state that no indications of heating were observed. Read any additional comments and explanations.<\/p>\n

Do not turn a technical conclusion into a stronger marketing claim. For example, a statement about heating should not automatically become a claim that every possible treatment is absent.<\/p>\n

Ask about diffusion or fracture filling separately where relevant, and check the scope of the particular report.<\/p>\n

Geographical origin<\/h2>\n

Some reports include an opinion on origin, such as Sri Lanka, Madagascar or Myanmar. Not every report includes this service, and an origin cannot always be determined.<\/p>\n

An origin opinion concerns where the stone formed, not the country where it was bought, cut or sold. A sapphire traded in Thailand is not necessarily of Thai origin.<\/p>\n

Colour and trade descriptions<\/h2>\n

Some laboratories provide colour-type descriptions when their criteria are met. Read the exact wording instead of inferring a designation from a photograph.<\/p>\n

GIA and Lotus do not necessarily use the same report format or colour terminology. A seller's \u201cRoyal Blue\u201d description and a laboratory's recorded colour type are different claims.<\/p>\n

Report number and verification<\/h2>\n

Use the issuing laboratory's official report-verification service. Compare:<\/p>\n