Round Brilliant
The round brilliant's 58 facets — 33 on the crown, 24 on the pavilion, plus the culet — were engineered by Marcel Tolkowsky in his 1919 thesis, "Diamond Design," written while he was a student in London. His specific proportions, including a 34.5° crown angle, a 40.75° pavilion angle, and roughly a 53% table, became the mathematical blueprint still referenced today, and the shape is sometimes still called the "Tolkowsky Brilliant." It's also the only shape with a fully standardized, formal cut grade from GIA — fancy shapes like oval, pear, and marquise don't get one yet, though GIA has announced it will begin grading select fancy shapes starting in 2027. Round brilliants also have the lowest yield of any shape when cut from rough, often retaining only around 40% of the original crystal's weight, which is a real driver of round's higher price per carat.
Princess Cut
The princess cut's path to the altar took a few steps. A 1961 "profile cut" by London jeweler Arpad Nagy set an early template, South African jeweler Basil Watermeyer refined it into a square, rounded-corner shape called the "Barion cut" in 1971, and the shape we know today as the princess cut was finalized around 1979–1980, credited to Betzalel (Bez) Ambar, Ygal Perlman, and Israel Itzkowitz. Its pointed corners are the most vulnerable part of the stone, so it's almost always set with protective V-tip prongs to guard against chipping.
Cushion Cut
A square or rectangular shape with softened, rounded corners and large, romantic facets — essentially a "pillow" shape. It's a direct descendant of the antique old mine cut, with 20th-century cutters keeping that familiar pillow outline while re-engineering the faceting using round-brilliant principles for better light return, which is why it shares that same warm, slightly vintage sparkle.
Emerald Cut
A rectangular step cut, meaning its facets run in long, flat, parallel rows like stair steps rather than the triangular facets of a brilliant cut. That structure creates a glamorous hall-of-mirrors flash instead of sparkle, but it also means the stone's large, open table shows off any inclusions or color more readily than a brilliant cut would at the same grade — because there's no faceting pattern to help camouflage them. GIA doesn't issue a standardized cut grade for emerald cuts the way it does for round brilliants, so evaluating one well really does come down to viewing the actual stone.
Radiant Cut
Designed in 1977 by Henry Grossbard, a master cutter with decades of experience, the radiant cut set out to combine the emerald cut's rectangular outline with the brilliance of round-style faceting. The result uses 70 facets and cropped corners, and it was one of the first diamond cuts ever patented — a versatile middle ground between an emerald's shape and a round's sparkle.
Pear Cut
A single-point teardrop shape with brilliant faceting that visually elongates the finger. Along with oval, marquise, heart, and sometimes radiant, pear cuts can show a "bow-tie" shadow across their center depending on how the stone's facets are arranged — worth viewing photos or video of the specific stone before you buy.
Marquise Cut
As the story is most often told in the trade, the marquise's elongated silhouette was commissioned by King Louis XV of France, who wanted a diamond shaped like the smile of his mistress, the Marquise de Pompadour. It's a charming story — and also one that doesn't hold up perfectly under scrutiny, since no primary historical source has ever confirmed it, which makes it worth treating as jewelry-trade legend rather than documented history. (You'll sometimes see the story told with Louis XIV instead, but that version has a clear chronology problem: Louis XIV died in 1715, six years before the Marquise de Pompadour was even born.) Whatever its true origin, the elongated shape does real work either way — its length maximizes the diamond's visual spread, often making it look larger per carat than almost any other shape.
Asscher Cut
A square step cut with cropped corners, patented in 1902 by Joseph Asscher of the Royal Asscher Diamond Company, a family firm in Amsterdam founded in 1854. It was the first diamond cut ever patented, protecting the design for roughly 40 years until the patent lapsed during World War II — and Joseph Asscher was also the diamond cutter entrusted with cleaving the enormous Cullinan Diamond in 1908. It's a quintessential Art Deco shape currently enjoying a strong modern revival, and like the emerald cut, its open facets call for higher clarity.
Heart Cut
A brilliant cut shaped into a literal heart outline, widely considered one of the most technically difficult shapes to cut well — both lobes and the center cleft have to mirror each other precisely, or the shape reads as lopsided. Like other fancy shapes, it doesn't currently receive a formal GIA cut grade.
Old Mine Cut
An antique, cushion-shaped predecessor to the modern round brilliant, cut by hand throughout the 1700s and into the late 1800s, with a high crown (40–50% of the stone's depth), a small table, and a deep pavilion (60–70% of the depth). Jewelry historians generally agree these deep, chunky proportions were shaped deliberately to perform well under flickering candlelight and gaslight — the only light most rooms had after dark — though the exact intentions of individual 18th-century cutters are naturally harder to document than the proportions themselves. The deep cut trades symmetry for that flickering, romantic sparkle.
Old European Cut
The early-1900s bridge between the old mine cut and today's round brilliant, hand-faceted on spinning wheels by cutters in Antwerp, Amsterdam, and New York roughly between 1890 and 1930 — a rounder outline, a small table, and a noticeably deep cut with a tiny flat culet visible as a pinprick at the very bottom when viewed face-up.
As a general rule, fancy (non-round) shapes carry a lower price per carat than round. A princess cut, for instance, can retain roughly 80% of a rough diamond's original weight during cutting, compared to only around 40% for a round brilliant — since a princess cut's square shape follows the diamond's natural octahedral crystal structure far more closely than a round's curved outline ever can.