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.
Above five carats, the buying process should slow down. Facet relationships are easier to see, outline decisions carry more visual weight and small condition or documentation issues can have large consequences.
Begin with facts
Confirm natural-diamond status, weight, measurements, colour, clarity, fluorescence, report number and current condition. Match the report through measurements, inscription and identifying features before discussing history.
Compare face-up presence
Large antique diamonds can carry weight very differently. Record length, width, depth and length-to-width ratio. A deep profile may support a high crown, or it may hide weight. View the stone face-up and from the side.
Step back from the stone
Study corners and shoulders close up, then look from normal wearing distance. Minor irregularity can become more prominent at scale. A ratio helps describe elongation, but the outline decides whether it feels elegant or awkward.
Use several lights
- Diffuse light for overall brightness.
- Small direct lights for fire and scintillation.
- Mixed room light for daily appearance.
- Neutral, unedited video for remote comparison.
Include ordinary room light and a magnified condition examination in the viewing.
Interpret clarity and condition
Ask whether inclusions are visible face-up, reduce transparency or reach a vulnerable girdle area. Request a condition map covering chips, cavities, naturals, abrasion, culet condition and possible repolishing. Location matters more than a tidy summary.
Keep provenance separate
Mine, age and ownership claims need evidence beyond a standard grading report. Useful records include dated invoices, archival descriptions, signed-jewel records, photographs, auction catalogues and a traceable sequence of owners.
Plan the setting and logistics
The setting must allow for girdle variation, corners, pavilion depth and culet clearance. Agree in writing who carries risk during shipment, inspection and return. For an important stone, use secure transport, suitable insurance and an independent gemologist working for an agreed inspection fee.
Keep one decision file
- Current verified laboratory report.
- Measurements and neutral photographs.
- Unedited videos in several lights.
- Condition map and setting notes.
- Provenance claims with supporting documents.
- Sale, return, insurance and shipping terms.
- Independent review notes.
Explore the current diamond dossiers, compare outlines in the Antique Cushion Diamond Atlas, or arrange a private review through Inspection and Service.