The parts of a diamond
| Part | What it is | What it does |
|---|---|---|
| Table | The large flat facet on top | The main window where light enters and brightness returns. |
| Crown | The upper section between table and girdle | Its angled facets split light into flashes of colour (fire). |
| Girdle | The narrow band around the widest point | Defines the outline, protects the edge, holds the laser inscription. |
| Pavilion | The lower, cone-shaped section | Acts like a mirror, reflecting light back up through the crown. |
| Culet | The tip at the very bottom | Usually a point or a tiny facet that protects the tip. |
| Diameter | The width measured across the girdle | Determines how large the diamond looks face-up. |
| Depth | The height from table to culet | Shown as a percentage of the diameter. |
The facets of a round brilliant
The crown carries the table, 8 star facets, 8 kite (bezel) facets and 16 upper girdle facets, 33 facets in total. The pavilion carries 8 main facets and 16 lower girdle facets, 24 in total, plus an optional culet facet. Together they create the famous pattern of bright and dark contrast that makes a brilliant sparkle.
Ideal proportions
There is no single perfect formula, but the most brilliant round diamonds fall within these ranges:
| Measurement | Excellent range | Why it matters |
|---|---|---|
| Table % | 53 – 58 % | Balances brightness and fire. |
| Depth % | 59 – 62.5 % | Too deep looks small and dark, too shallow looks glassy. |
| Crown angle | 33 – 35.5° | Creates colourful fire. |
| Pavilion angle | 40.6 – 41° | Reflects light back to the eye. |
| Girdle | Thin to medium | Protects the edge without hiding weight. |
| Culet | None or pointed | Invisible from above. |
When proportions go wrong
A diamond cut too deep hides weight in its lower half, looks smaller than its carat suggests and can show a dark centre. A diamond cut too shallow looks wide at first, but light escapes through the pavilion and a dull ring, often called a "fish-eye", appears. A thick girdle adds weight that you pay for but cannot see.
Symmetry and polish
Beyond proportions, laboratories grade how precisely the facets meet (symmetry) and how smooth their surfaces are (polish). Excellent symmetry and polish keep the light path clean, which is why we choose centre diamonds with excellent cut, polish and symmetry.
