Prepared by the Imperial Cushions editorial team. Laboratory terminology is retained where a report is cited; historical context and dealer judgment are identified as interpretation.
A grading report identifies and describes the diamond. Read its measurements and grading findings beside the photographs, movement video and condition examination.
Match the report to the diamond
Record the laboratory, report number and date, then verify the report with the issuer. Match the measurements, inscription and plotted characteristics. If an older report differs from the stone, stop and ask whether it was repolished, recut or damaged.
Read measurements before weight
Carat records weight. Length and width describe the footprint; depth shows how far the stone extends below the table. Divide length by width for the ratio, then inspect the corners and shoulders in the face-up view.
Confirm the cutting style visually
Report terms such as “old mine brilliant” or “cushion modified brilliant” can cover stones with different facet patterns. Use the wording as classification, then inspect the central facets, pavilion mains, crown and culet in motion.
Read colour in context
Laboratories grade colour under controlled conditions. Face-up appearance can still change with cut, fluorescence, metal and lighting. View the stone face-up and from the side before deciding that the higher letter must be the prettier diamond.
Read clarity by location
The grade summarises internal and external characteristics. Ask whether an inclusion is visible face-up, affects transparency or reaches a thin corner or girdle section. Check the plot and comments, then inspect the loose stone if possible.
Fluorescence is a description
The entry records the reaction to long-wave ultraviolet light. Inspect transparency, colour and contrast in daylight and ordinary indoor light, and compare those observations with the recorded UV response.
Read every comment
Comments may mention clouds, graining, inscription details, treatments or additional features. The small print can be more useful than the large grade.
Documentation for history and provenance
Use dated, traceable records to research a mine source, cutting date, historic owner or collection. A diamond-type letter records crystal classification; provenance research follows the documentary history of the individual stone.
Report-to-stone checklist
- Verify the report with its issuer.
- Match measurements, inscription and clarity features.
- Compare face-up spread and length-to-width ratio.
- Inspect outline, girdle and culet under magnification.
- Watch brightness, contrast and fire in several lights.
- Read every comment and discuss the intended setting.
Browse the current diamond dossiers, compare real outlines in the Antique Cushion Diamond Atlas, or arrange a documented review through Inspection and Service.
Reference: GIA diamond grading services. Report formats can change, so verify the current document with its issuer.