The Brilliant Cut
There was no single inventor of the brilliant cut although it is often credited to a seventeenth-century Venetian lapidary named Vincenzio (or Vicenzo) Perruzzi, about 1700. Onc faceted cut is named after him. Rescarch by H. Tillander has shown that the Perruzzı family came from Florence and that there is no record of a member named Vincenzio. Faceted diamonds based on the octahedron with rounded corners or cushion outlines, as well as the more modern conical shapes with round outlines, were all called brilliant-cut diamonds and referred to colloquially as brilliants. An increase in the cutting of brilliants occurred about mid-seventeenth century, and the eighteenth saw a spate of re-cutting to modernize old cuts. This was partly due to the awakening of interest in technical innovation and partly due to the waning interest in the invariable classical form of the table stone. Rough stones were often rounded by the immensely laborious process of hand bruting if they were of octahedral form.
Many cutters, however, according to Tillander, found that rough of approximately rhombic dodecahedral form lent itself naturally to the fashioning of brilliant-cut stones. As there were insufficient crystals of dodecahedral shape, someone named Perruzzi may have invented a similar design from octahedral rough. The discovery of the Brazilian deposits gave great impetus to the brilliant cut in a form known as the triple cut, shown in, and today usually referred to as old-mine cut. The girdle outline is cushion-shaped and there are thirty- three facets on the crown and twenty-five on the pavilion, making fifty-eight in all, the same as the modern brilliant. Another name for these stones is old- miners.
Even as late as 1750, the English jewellei David Jeffries thought the brilliant cut to be a whim of fashion and that the rose cut would outlive it, but over the next two centuries large numbers of old roses were re-cut to brilliant form with 'dreadful sacrifice of weight', as C. W. King put it in 1870. Some cuts illustrated by Jeffries are shown in. Smaller and less valuable stones were double cut instead of being triple cut. The double cut was an older style with a square table and sixteen other facets on the top with duplicate facets on the bottom, except that the cut was much smaller than the table, making a total of thirty-four. There was an English double-cut brilliant that had the triangular corner facets reversed so that the table became octagonal and the centre of an eight-rayed star, while the pavilion remained similar to that of the double cut except for the loss of four corner facts . The outline of the girdle of a stone depended much more on the form of the crystal before it was cut in earlier days than today because the problems of manufacture were greater. Most girdle outlines became cushion-shaped, as already mentioned, but some were almost or quite round and others of rounded Pear-shaped triangular shape, when the facets were grouped in threes instead of fours. Other crystals lent themselves to the manufacture of oval or brilliants. brilliance has not always been achieved. Most historical diamonds were cut in modifications of the brilliant form, although the original cut of some was different. The retention of weight has been an important consideration when cutting or re-cutting, however, so that the full In the nineteenth century, more rounded brilliants appeared and with these and cushion shapes, English cutters tended to make thinner girdles than Dutch cutters, an indication of origin.
The Modern Brilliant Cut
The modern brilliant cut came about with the publication of the ideal dimen- sions in a theoretical treatise on the subject by Marcel Tolkowsky in 1914. The angles of the pavilion to the girdle and the angle of the crown had been largely determined by the octahedral crystal angles although some cutters particularly in New York, U.S.A., had previously been experimenting and discovered that they could increase brilliance by reducing these angles.
Making brilliant Tolkowsky's ideal cut involved much more work on the rough material and encouraged the introduction of machine brushing to round the crystals and machine sawing to shape material. Not all brilliant cut-diamonds were cut to the ideal proportions by any means, but Tolkowsky's work had a very important influence on the cutting of larger and higher quality material. Lower quality rough was cut to retain maximum weight, as it is today. The brilliant cut with the round girdle became almost universal. The culet was small, but still very noticeable through the table, and the facets below the girdle reached about half-way down the pavilion, as shown in. After the Second World War, there were further small modifications. The lower girdle facets became gradually longer, some extending to eight-tenths the distance down the pavilion, and the table tended to become larger, resulting in a shallower crown.
Variations of the Brilliant Cut
The brilliant cut is applied to shapes other than the conical or standard brilliant They include the boat-shaped marquise or navette cut, the pear-shaped pendeloque cut, the oval brilliant cut, and the heart-shaped brilliant cut. They are shown in It has been pointed out that for a gem such as diamond, depending for some than of its beauty on colour dispersion, the number of facets should be increased with 0-1 18 in (3 mm) or shorter than 0.019 in. (mm), from which it follows that stones of over 10 carats should have more than fifty-eight facets, and those of under -carat (about twelve points) should have fewer facets to give maximum brilliance In fact most small stones today are made as sight-cuts (single-cuts), or Swiss- cuts, with fewer facets as shown in. For larger stones there are several modifications of the brilliant cut with more facets, including the Jubilee with eighty-eight, the King with eighty-six, and the Cairo star cut with seventy-four, as shown in.
Faceted Girdles
The girdle of a brilliant-cut diamond is normally left in its bruted state, which is matt, so that it reflects very little light internally. The loss is very small if the girdle is of normal width. A few cutters concerned with high quality do facet or polish the girdles of stones, however. Louis H. Rosclar in the U.S.A. placed forty small facets around the girdle. A. Monnickendam in England polishes the girdle in a circle without facets by a special technique. Patents on faceted girdles have now expired and some other cutters add them to the standard brilliant-cut. In one version, known as the Royal 144, forty extra facets are placed on the girdle, and forty-eight more, as a 'wreath' of extra cross, skill and kite facets on the pavilion near the girdle. These are claimed to add to the stone's brilliance, but can hardly do so. Small facets are today often cut very rapidly by automatic processes. Girdles of polished stones that are not round, including pendeloque, emerald, and square cuts, are ground and polished. The girdle of marquise stones can be bruted or ground and polished.
Step and Square Cuts
A step or trap cut may have pointed or bevelled corners. When such cuts are bevelled, they are often called emerald cuts. Diamonds cut thus naturally lose brilliance and lustre because the cuts are not ideal from the point of view of beauty. The proportions of both can vary from square or almost square to a long oblong, depending on the shape of the original crystal. Steps cuts are often made from octahedra that are elongated in one direction. When the shape is very clongated in relation to its width, the cut stone is called a baguette after the long French loaf, shown in It is possible that the earliest baguette diamonds were produced in India by cleavage in a dodecahedral direction from an octahedral crystal to give long, boat-shaped chips. The most common fault in an emerald or square-cut stone is a window, a facet through which one can see, looking at the stone from the table. The number of steps is unimportant, but to avoid windows, the pavilion facets should be cut at greater than the critical angle of 24° 26'. This is sometimes difficult, if not impossible, particularly with the end pavilion facets of an elongated octahedron crystal As the pavilion of a step or square-cut stone is deeper than that of a brilliant cut stone, the crown should be shallower, in order to make the overall depth about the same as an equivalent brilliant.
Brilliant Square Cut
The fact that square and emerald-cut diamonds lose so much in brilliance, fire and scintillation compared with round brilliant-cut stones does not often com- pensate for the extra weight retained by the square or emerald cut. With this in mind, and the call by jewellery designers for a brilliant square cut, a Johannes- burg cutter and polisher, Basil Waterme achieved in 1971, after many years of experiment, the most brilliant square cut so far. Called the Barion cut, combining his wife's name Marion with his initial, it has twenty-five facets on the crown and twenty-nine on the pavilion, a total of sixty-two, as shown in. There are half-moon facets just below the girdle (which is polished) on each side. This enables an emerald-cut pavilion to be superimposed on a modified brilliant-cut pavilion. The design provides more scintillation than a normal step cut because, when the stone is tilted, the steps on the crown break up the reflections from the pavilion to provide a fountain-like pattern.
Among other cuts employed in modern times are two designed for macles, the 48-facet troidia, devised by Edouard Sirakiar in Belgium, and the new trilliant developed by Asscher's Diamant Maatschappij in Amsterdam, Holland, which has forty-four facets and a polished girdle . P. Lancon of Geneva, Switzerland, developed a star-shaped cut and another Belgian cutter and polisher has managed to produce many shapes including the horse's head shown in. In 1960, a London cutter, A. Nagy, introduced an unusual and economic cut for flat crystals to give a large superficial area of diamond. It was at first called the Princess cut and is now the profile cut. The shape, shown in, is based on a cut originally developed for diamond tools used for dressing grinding wheels. It comprises a series of V-grooves on the back of the stone at the angle shown in the diagram. The cut is lively, but lacks fire.
