An HRD report — formally issued by HRD Antwerp (Hoge Raad voor Diamant, meaning High Diamond Council) — is an independent gemmological certificate assessing the quality characteristics of a polished diamond or, in certain report types, a coloured gemstone. Founded in 1973 and headquartered in the Antwerp diamond district, HRD Antwerp has operated for more than five decades as one of the principal grading authorities in the European diamond trade, alongside the Gemological Institute of America (GIA) and the International Gemological Institute (IGI).

What an HRD Diamond Report Covers

The standard HRD diamond grading report evaluates a polished stone across the four principal quality parameters — carat weight, colour, clarity, and cut — collectively known in the trade as the 4Cs. The laboratory's grading scales are aligned with internationally recognised conventions, making HRD certificates broadly comparable with those of other major laboratories, though minor inter-laboratory variance in borderline grades is well documented across the industry.

• Carat weight is recorded to two decimal places for stones above a threshold size.
• Colour is graded on an alphabetical scale (D through Z for colourless to light yellow/brown), consistent with GIA's established nomenclature.
• Clarity is assessed under 10× magnification and reported using standard grades from Flawless (FL) through Included (I1–I3).
• Cut evaluation encompasses proportions, symmetry, and polish, each graded on a descriptive scale from Excellent to Poor.

Larger or more significant diamonds may be accompanied by a plotting diagram — a schematic map of internal inclusions and surface blemishes — which assists in stone identification and provides a permanent record of the stone's unique characteristics.

Report Types

HRD Antwerp issues several distinct report formats to serve different segments of the trade:

• Diamond Grading Report: the full certificate for polished diamonds, typically used for stones of 0.30 ct and above.
• Diamond Identification Report: a condensed document confirming natural diamond status and basic quality parameters, often used for smaller or lower-value stones.
• Coloured Stone Report: an identification and quality assessment for coloured gemstones, addressing species, variety, and, where applicable, treatment disclosure.
• Origin Report: a geographic origin determination service for diamonds and select coloured gemstones, drawing on spectroscopic and inclusion analysis.

Laboratory Standards and Market Position

HRD Antwerp's grading protocols are subject to ongoing calibration and are conducted by trained gemmologists working under controlled lighting conditions standardised to 6500 K daylight-equivalent illumination — the same colour temperature adopted by most major laboratories for colour grading. The laboratory is accredited under ISO/IEC 17025, the international standard for testing and calibration laboratory competence, lending its reports institutional credibility beyond the diamond trade itself.

Within the European market, and particularly in Belgium, the Netherlands, and parts of the Middle East, HRD certificates carry significant commercial weight. Antwerp's historical role as the world's foremost diamond trading and cutting centre has reinforced the laboratory's authority: a substantial proportion of the world's rough diamonds have historically passed through the city, and HRD's proximity to that trade has shaped its grading culture and client base.

Considerations for Buyers and the Trade

As with any laboratory report, an HRD certificate describes a stone at the time of grading and does not constitute a valuation or appraisal. Prices realised at auction or in private sale depend on market conditions, demand for specific qualities, and the reputation of the issuing laboratory in the buyer's home market. Buyers sourcing stones for markets where GIA certification predominates — notably the United States — should be aware that some trade participants assign a modest premium to GIA-graded stones, reflecting familiarity and liquidity rather than any inherent difference in stone quality. Conversely, in European and certain Asian markets, HRD certificates are well understood and fully accepted.

Treatment disclosure is a mandatory component of HRD reports: any detected clarity enhancement (such as laser drilling or fracture filling) or colour treatment (such as HPHT processing) is noted on the certificate. Synthetic diamonds are identified and reported separately from natural stones.

Further Reading

• GIA — Understanding Diamond Grading Reports (gia.edu)