Diamonds have been coveted by humans for thousands of years, and a typical natural diamond crystal - the octahedron - is pictured above. But when did we start cutting the octahedron into the bright and flashy round stones we see in jewellery today?
The first and only known form of diamond polishing up to the 14th century was the point cut. Essentially, in this cut, the natural octahedral shape was improved by polishing faces that were not perfectly flat. It's also been suggested that point cuts were polished from macles, which are triangular shaped diamond crystals. In essence, the point cut sought to mimic and improve upon nature.
Point cuts could only be produced because the diamond cutters of time had realised that only diamond can cut and polish another diamond, and aside from laser cutting, this remains true today.
The table cut appeared during the 15th century. On a table cut stone, the top tip of the octahedron has been polished/ground away. The sloping sides would also be polished to create four facets. Culets - the small polished facet on the bottom of the stone where the points meet - started to appear around this time. It's likely that by now, cutters had began to appreciate and understand the optical effects diamond was capable of, namely brilliance and fire.
Table cuts remained popular up to the 17th century, and older point cuts were ground down to create table cuts.
Rose Cuts and Briolettes
A diamond dodecahedron crystal
Table cuts were not suited to dodecahedrons (another diamond crystal habit) nor irregularly shaped stones, and many diamond crystals fall into these groups.
The rose cut was introduced in the early 16th century and features a flat base with a faceted dome. Rose cuts are incredibly beautiful stones: they lack the fire and brilliance we see in modern stones, however, they do show a certain amount of lustre, and it is this that they were prized for.
The facets on a rose cut are usually triangular in shape and stones can be double-sided. Drop-shaped, double-sided rose cuts are known as briolettes.
Rose Cut diamonds in antique ring from Europe
Single and Double Cuts
Single vs Double (Mazarin Cut)
Single cuts, also known as eight cuts, are the first real leap towards the round stones we see in our jewellery today. In single cut diamonds, 4 'corner' facets were polished on the crown and pavilion of a table cut, bringing the facet number up to 18 (or thereabouts).
Double cuts, sometimes referred to as Mazarin cuts, came next and generally have 34 facets including a large culet. It is with the double cut that brilliance and fire began to improve.
Bruting (the process of mechanically turning one diamond against another to make the stone round) had not yet been invented, but the outline of stones began to be shaped by a diamond on diamond abrasive scraping method known as kerfing. This tended to produce more cushion-shaped stones than round.
Old Mine Cut
By the mid-17th century, diamond cutting had leapt forward to the 58 faceted triple cut. The first triple cut was known as the old mine cut, and the stones remained cushion shaped rather than round. As the diamond saw had not been invented (to cut the top off the octahedron), crowns and pavilions were bulky.
Today, ideally, an octahedron makes two polished diamonds. The top of the octahedron is sawn off to produce a smaller diamond, and the remaining larger section is cut and polished into a larger diamond. This gives the diamond manufacturer the best yield (monetary return).
Since it wasn't possible in the 17th century to saw the top off the octahedron, only one polished diamond was made from the crystal, and to maximise the weight of the cut stone, it was made as bulky as possible.
Diamond's brilliance really started to shine with old mine cut stones.
Mechanical bruting was introduced in the 1820s, enabling the production of much rounder stones. The diamond saw had still not been invented, meaning that while the stone's outline was now round, the crown and pavilion remained bulky. Bulky stones do not deal with light quite like modern cuts do, so these older stones are still not as 'firey' as the stones we see today.
The faceting on old European cut stones tends to be more symmetrical than on old mine cuts, though still not as precise and symmetrical as on modern diamonds.
The early 20th century saw the invention of a diamond saw: a blade, coated in diamond grit, that made it possible to saw the top off the octahedral crystal.
Flatter crowns with larger tables became common place as diamond cutters began experimenting with the proportions of stones to find the 'ideal cut'. You will spot transitional cut stones in jewellery dated approx 1920s to 1940s. When you do, you'll notice that transitional cut stones are different to old Europeans, but not quite 'right' in terms of how we see modern stones proportioned today.
To identify: look for smallish culet on a symmetrical stone with a lower crown. Each stone was a experiment in optimum angles.
Modern Round Brilliant
The stones we see and love today. 57 facets (58 if a culet is visible) - 33 on the crown and 24 on the pavilion. This cut, for which the proportions are exact, makes best use of diamond's dispersion (fire) and produces a high degree of brilliance (light return). You'll find these modern round brilliant cut stones from about the 1950s onwards.
Of course, there are many more cuts today than those shown above - the oval, the princess, the calibre, the marquise, the emerald, the asscher and so on. But the overview above shows the transition from ancient times to the most popular cut by far today: the round brilliant.
Brilliance: the degree of brightness/light return when the diamond is viewed face up. Brilliance is both an internal and external reflection effect.
Lustre: the shine from the surface of the stone - the quality and quantity of light being reflected back.
Fire: the flashes of spectral colour you see as a diamond is moved about under light. Also referred to as dispersion.
Crown: top section of the cut diamond
Pavilion: bottom section of the cut diamond
Culet: the point/tip at the bottom of the stone where all angles/facets meet.