Brilliant cut and step cut
Every cut belongs to one of two families. Brilliant cuts have triangular and kite-shaped facets arranged around the table that split light into many small flashes: round brilliant, oval, pear, marquise, heart, princess, radiant and most cushions. Step cuts have long, parallel facets in tiers that show broad planes of light: emerald and Asscher. Step cuts hide inclusions and colour less and therefore call for higher clarity.
The seven cuts
| Cut | Report term | Facets | Length-to-width ratio | Particular |
|---|---|---|---|---|
| Round brilliant | Round Brilliant | 57–58 | 1.00 | Only cut with a GIA cut grade |
| Oval | Oval Brilliant | 56–58 | 1.30–1.50 | Looks larger than a round of the same weight |
| Emerald | Emerald Cut | 57 (varies) | 1.30–1.50 | Step cut, clarity especially important |
| Cushion | Cushion (Modified) Brilliant | 58–64 | 1.00–1.10 (square) | Two facet variants, holds colour |
| Princess | Square Modified Brilliant | 50–58 | 1.00–1.05 | Pointed corners, much weight in depth |
| Pear | Pear Brilliant | 56–58 | 1.45–1.75 | One point, bow-tie possible |
| Marquise | Marquise Brilliant | 56–58 | 1.75–2.25 | Two points, largest surface per carat |
Round brilliant
The round brilliant is the most thoroughly researched cut. Ideal proportions exist for it (Tolkowsky 1919) as well as a GIA cut grade from Excellent to Poor. Anyone looking for the strongest sparkle starts here. Its drawback: cutting it loses the most material from the rough.
Oval
An elongated brilliant with the same facet principle. The shape looks longer on the finger and larger at the same weight. Watch for the bow-tie, a dark band across the middle that can occur in elongated cuts and appears on no report – you only see it on the stone.
Emerald
The classic step cut with cut corners. Instead of sparkle it shows broad planes of light, the "hall of mirrors" effect. The large table acts like a window: inclusions and tints are more visible than in brilliant cuts, which is why clarity grades from VS1 and colours from G–H are advisable.
Cushion
Square or rectangular with rounded corners, the outline of the historical old mine cut. The report distinguishes "Cushion Brilliant" (large pavilion facets, broad flashes) from "Cushion Modified Brilliant" (an extra row of facets, fine sparkle, "crushed ice"). Cushions hold colour slightly more than round brilliants and are therefore often chosen for fancy colours.
Princess
A square brilliant cut with pointed corners; "Square Modified Brilliant" on the report. It retains much weight from the rough but carries part of it in depth. The pointed corners are vulnerable and are protected by prongs in the setting.
Pear
One rounded end, one point. Usual ratios 1.45–1.75; symmetry – point on the centre axis, even shoulders – matters more here than in round stones. The point is protected in the setting; the bow-tie is almost always present and varies in strength.
Marquise
Two points, also called navette. No shape shows more surface per carat. The two halves must mirror each other; both points should be protected. The bow-tie occurs more often than in the pear.
Bow-tie, windows and other light phenomena
Some appearances are on no report and can only be judged on the stone. The bow-tie is a dark band across the middle of elongated brilliant cuts (oval, pear, marquise) that arises because the pavilion facets in the centre do not return light to the viewer; faint, it is normal; pronounced, it disturbs. A window shows in stones cut too shallow: you see through the table onto the background. Crushed ice describes the fine-grained sparkle of modified cushions and radiants, in which individual flashes can hardly be told apart – a matter of taste, not a defect. The hall of mirrors in the emerald cut is the intended interplay of bright and dark planes.
Setting by cut
The shape determines how the stone should be set. Round brilliants sit in four or six prongs or in a bezel. Princess cuts need prongs over the four corners, pears and hearts a prong at the point, marquises at both points – the points are where a diamond can chip on impact. Emerald cuts and Asschers are often set in bezels or with double prongs at the cut corners. Anyone who buys the stone first and chooses the setting later should give the goldsmith the report: the measurements in millimetres are the basis for the setting.
How to recognise a good cut
In a round brilliant, by the cut grade. In all other shapes by three things: polish and symmetry "Excellent" or "Very Good" on the report, a length-to-width ratio in the usual range of the shape, and a look at the stone or a good photograph – because of bow-tie and window. In doubt, comparing two stones side by side helps more than any number.
Which cut for whom
That is a matter of taste, and none of the shapes is "better". Three practical notes: step cuts call for higher clarity. Elongated cuts (oval, pear, marquise) are best judged on the stone or in a photograph because of the bow-tie. And with pointed shapes (princess, pear, marquise, heart) the setting is part of the planning.
Every cut has its own overview page in our shop listing all stones of that shape: round brilliant, oval, emerald, cushion, princess, pear and marquise.