Diamond grading and diamond appraisal are two distinct services that are often confused — but they serve very different purposes. Understanding the difference is important whether you are buying, selling, insuring or inheriting diamonds or jewellery.

What Is Diamond Grading?

Diamond grading is a technical assessment of a diamond's physical characteristics — specifically the four Cs: cut, colour, clarity and carat weight. A grading report describes the stone objectively, using internationally recognised standards and terminology.

The most widely recognised grading authority in the world is the Gemological Institute of America (GIA). A GIA grading report — sometimes called a GIA certificate — is accepted by buyers and sellers worldwide as an objective, reliable assessment of a diamond's quality. Other recognised grading bodies include the IGI (International Gemological Institute) and HRD Antwerp.

Grading is performed on loose diamonds, not stones set in jewellery — the setting makes accurate assessment impossible.

What Does a Grading Report Tell You?

A full diamond grading report includes the diamond's shape and cutting style, measurements (in millimetres), carat weight, colour grade, clarity grade, cut grade (for round brilliants), polish and symmetry grades, fluorescence, and a plotting diagram showing the location of any inclusions. Some reports also include a proportion diagram and additional quality assessments.

What Is Diamond Appraisal?

A diamond appraisal assigns a monetary value to a diamond or piece of jewellery. It answers the question: what is this worth in today's market? An appraisal document states the appraised value of the item — which may be the replacement value (what it would cost to replace the item), the fair market value (what a willing buyer would pay), or the insurance value.

Appraisals are performed by qualified gemologists and jewellery appraisers. They consider the quality of the diamond (using grading standards), the metal and craftsmanship, and current market conditions.

When Do You Need Grading?

You need a grading report when buying or selling a loose diamond — it provides objective, third-party confirmation of the stone's quality. You also need grading when you want to verify the quality of a diamond you already own, when considering recutting a diamond (the report establishes the before state), or when trading diamonds professionally.

When Do You Need Appraisal?

You need an appraisal for insurance purposes — most insurers require an appraisal document to cover jewellery. You also need appraisal for estate planning and inheritance, for resale (to establish a fair asking price), and for pre-purchase assessment (to confirm that the price being asked is reasonable for the quality being offered).

Can One Document Serve Both Purposes?

A grading report is not an appraisal — it does not assign a monetary value. An appraisal typically incorporates grading information but goes further by assigning a market value. For insurance purposes, you generally need an appraisal document, not just a grading report.

Jay Gems Bangkok Grading and Appraisal Services

Jay Gems provides professional diamond grading assessments to GIA methodology and jewellery appraisals for private clients, jewellers and dealers across Bangkok, Singapore and Hong Kong. Our team has assessed thousands of stones across all shapes, sizes and qualities. Contact us to arrange a grading or appraisal assessment — in person at our Bangkok showroom or by secure international shipping.