- Girdle
- Natural crystal faces (naturals)
- Extra facets
- Twinning lines
- Growth lines
- Damage
- Nicks and fractures
- Indentations, damage to edges, scratches
- Polishing marks
- Knots
- Burn marks
Apart from proportions and symmetry, external features are taken into consideration when grading for cut. Evaluation with 10 x magnification is decisive.
External features may occur in large numbers and in manifold forms. In order to classify them, they have been divided into three main groups:
- natural features
- features caused during cutting
- features resulting from damage
In this, natural features are the least strictly judged, those caused during cutting and those resulting from damage are more heavily penalized.
The following external features occur in cut diamonds:
| natural crystal faces (naturals)
twinning lines growth lines |
= natural features |
| fringes at the girdle rough girdle rough culet burn marks polishing marks traces of cutting extra facets |
= features caused during cutting |
| nicks fractures indentation marks scratches damage to edges |
= features resulting from damage |
| Symmetry of the girdle | Girdle |