Modified Brilliant — Brilliant-Style Cuts in Non-Round Outlines
Modified Brilliant — Brilliant-Style Cuts in Non-Round Outlines
GIA terminology for oval, cushion, pear, marquise, and other shapes with brilliant-pattern faceting
Modified brilliant is the term used in GIA grading reports and trade communication for any brilliant-cut gemstone in which the standard round-brilliant facet plan has been adapted to a non-round outline or to accommodate the irregularities of a particular piece of rough. The most common modified brilliants are oval modified brilliants, cushion modified brilliants, pear modified brilliants, marquise modified brilliants, and heart modified brilliants. Each retains the basic principle of brilliant faceting — facets arranged in patterns radiating from a culet on the pavilion and from a table on the crown — but distributes those facets across a non-round shape with such adjustments as the shape requires.
Why modifications are made
Two motivations drive most modifications: the shape of the rough, which often does not lend itself economically to a strict round brilliant, and the optical character desired by the cutter. A piece of rough with significant length-to-width asymmetry can be cut as an oval modified brilliant with high weight retention, where forcing the same rough into a round brilliant would waste a third or more of the original mass. A pear-shaped rough naturally invites a pear modified brilliant. A cushion shape can rescue a piece of rough whose girdle is squarish but whose corners do not allow a precise square outline.
Optical considerations also motivate modification. A cutter producing a modern cushion may add chevron-shaped facet rows to the pavilion to create the crushed-ice optical effect now in fashion; a cutter producing a long oval may shape the pavilion to suppress the bow-tie effect characteristic of poorly cut ovals; a marquise may receive specific facet adjustments to even the brightness across its tapered length.
How GIA terminology distinguishes the categories
GIA grading reports distinguish several styles of brilliant-cut diamond. Round brilliants receive the simple description round brilliant. Non-round brilliants whose facet plan follows the standard cushion or oval brilliant plan but in a non-round outline are described as cushion brilliant or oval brilliant. Stones with an additional facet row, alternative facet shapes, or other deviations from the standard brilliant plan receive the modified brilliant designation: cushion modified brilliant, oval modified brilliant, and so on.
The distinction matters in practice because the optical character of a modified brilliant differs from that of a strict brilliant in the same outline. A cushion modified brilliant typically has the busier, smaller-flash crushed-ice appearance, while a strict cushion brilliant tends to produce broader, more languid flashes characteristic of antique cushions. Buyers who understand the distinction can match the cut style to their preferred optical character.
Coloured stones
The modified brilliant terminology also applies to coloured stones, where modifications are even more common because coloured-stone rough is generally more irregular than diamond rough and the per-carat price escalates more sharply with size. Most ovals, cushions, pears, and marquises in commercial coloured-stone production are modified brilliants in the technical sense, with extra facet rows on the pavilion to retain weight and even out brightness. The cutter's skill in adjusting the modification to the specific rough is a major determinant of the resulting stone's quality.
Buyer's perspective
For buyers, the practical question is whether the modified brilliant in front of them returns light evenly across the face. A well-cut modified brilliant of any outline will look bright from edge to edge, with no obvious dark patch in the centre or sustained windowing. A poorly cut modified brilliant will show a window — a patch of transparency in the centre where the eye sees through the stone rather than seeing reflected light. The modification, in itself, is neither good nor bad; what matters is whether the cutter has used the modification to produce a beautiful stone or whether the modification is a workaround for problematic rough that compromises optical performance. See also: oval modified brilliant; cushion modified brilliant; pear modified brilliant.