Antique diamond knowledge
An open culet is a small polished facet at the bottom of a diamond, where a pointed tip would otherwise be. It is common in old mine and old European cuts. Face-up, it may look like a central opening or dark geometric point.
Reviewed 3 September 2026. Prepared by the Imperial Cushions editorial team from public dossiers and the cited GIA material.
What the culet is
The culet sits opposite the table where the pavilion mains meet. A small polished facet reduces the vulnerability of a sharp point while the diamond is loose. GIA describes visible culets from Very Small to Extremely Large.
Viewed through the table, this flat, polished facet can appear light or dark as the lighting, viewing angle and surroundings change.
Why antique cuts have visible culets
Old mine cuts often combine a small table, high crown, deep pavilion, short lower-half facets and visible culet. The culet protected the pavilion tip and became part of the cut’s architecture.
A visible culet may create a quiet centre around which broad flashes move. It can also be too dominant or poorly placed. Judge it inside the whole pattern alongside the table, crown and pavilion.
Culet, chip or abrasion?
| Observation | Likely meaning | Best check |
|---|---|---|
| Flat, deliberate bottom facet | Intentional culet | Report, pavilion view and magnification |
| Irregular missing area | Possible chip | Several magnified angles |
| Frosted wear along an edge | Possible abrasion | Diffused light and condition video |
| Dark centre that moves on tilt | Often reflection or obstruction | Slow movement in more than one light |
Inspect the culet from several magnified angles. Use the antique diamond condition guide and the grading-report guide beside the stone.
How culet size changes the pattern
A small culet may read as a pinpoint. A larger one may become a clear geometric window. Visibility also depends on table size, pavilion depth, facet scale, contrast and distance.
Compare the culet with the complete proportion set. Our proportions guide explains how table, depth, crown and outline work together.
Two stones, two readings
In the 8.01 ct H VVS2 dossier, the culet is easy to locate within a spacious field of broad facets.
The 3.01 ct G VS2 dossier is more compact. Outline, facet scale and contrast change the balance.
Watch the centre move
Watch whether the culet darkens, brightens or recedes as the surrounding facets reorganise. Repeat at normal screen distance. Follow the video review with physical inspection of the culet and girdle.
Buyer’s checklist
- Read the culet description on the report.
- Request straight face-up and pavilion views.
- Watch slow movement in more than one light.
- Use magnification to separate the facet from damage.
- Return to the whole diamond and judge the balance.
Record the culet as a facet of the cut, document any chips or abrasion, then decide whether its size and position suit the overall pattern.