The Pyramidal Point Cut

(via Diamond Cuts in Historic Jewelry:1381-1910) Herbert Tillander writes:

In sixteenth-century portraits, the sitter frequently wears a pointed diamond, but too many of these Point Cuts are drawn with abnormally high proportions. They cannot possibly all have been fashioned from triangular types of rough. The reason for their unusual height must have been the artist’s belief that the sharper the stone was, the better it would serve its serious purpose—as a script diamond—of inscribing love devices on the beloved’s window!

It would be possible to give coutless examples of diamond jewelry of the Middle Ages, as well as some from later periods, and explain their symbolism. The exquisite ‘Palatine’ or ‘Bohemian’ gold crown, also called the ‘Crown of an English Princess’, was made around 1370-80. It was originally decorated with a large number of diamond crystals, all about 2mm in size. Most have been lost, but twenty-two have been preserved and are still in the crown. They appear to be naturally rounded octahedrons. Some of them may have been slightly fashioned in order to match the others, and certainly most of them were rubbed with some sort of polishing agent.

Irregular octahedrons were being fashioned at least towards the end of the fourteenth century, since inventories of the beginning of the fifteenth century already mention both fait and non faite, or naif and ‘cut’. The task of the earliest diamond cutters was to improve symmetry and achieve full transparency by smoothing the faces and giving them a high polish. This could be done by grinding, preceded when necessary by bruting; this always had to be done in a direction which diverged at least one or two degrees from the so-called ‘divine angle’ of crystallization (i.e. about 54¾º).

It also seems indisputable that some particularly ingenious cutters of the time had mastered the art of cleaving, which in those days was practised only in great secrecy. They had discovered, by trial and error, that diamonds have ‘grain’—that is, specific directions in which they can be worked—and from then on they were able to create gems of almost any shape, not only those of a natural crystal, though initially these were the shapes most imitated, since it was believed that a diamond must appear natural and untouched in order to retain its magical powers.

Distorted octahedrons, broken apexes, crooked edges and other irregularities occasioned by nature prompted cutters to apply additional faceting on crystals which, though basically octahedrons, showed traces of cube or dodecahedron or both. Given the slightly convex shape of diamond faces, it would not be difficult to apply small triangular facets by grinding. Sometimes extra ‘fancy facets’ could be added to disguise disturbing flaws or natural fractures.

No cutter would want to reduce the apparent ‘size’ (i.e. the width of the girdle plane) of a bipyramid, but the height of the crown or the depth of the pavilion could be reduced without too much affecting the ‘size’. Grinding (if this was to be the method used for fashioning) had to start from the center of a face and proceed towards both the girdle and the apex, gradually lowering the height of the gem. It could be left slightly rectangular or with one or more of the corners blunted.

It is possible to tell whether the height of a pyramidal crystal has been lowered by looking at the internal square reflection visible in every diamond of pyramidal shape. Other reflections can also be seen between this large reflection and the corners of the stone but these are of no interest at this point unless a tiny square appears round the apex, which indicates that the biyramid is too high for an octahedron and that the gem has therefore been fashioned from an entirely different crystal shape—a was, for instance, or a dodecahedron.

The extraordinary octahedral form of the crystal gave the cutter three squares from which to choose the one that would serve as the girdle. He usually chose the direction which would give the final stone the largest size, unless there were good reasons for choosing another direction (e.g. irregularities in the crystal, inclusions or faults in symmetry). For each possible solution there would be two apexes, one of which would eventually be symmetrized and fashioned into an attractive upper pyramid. If necessary, the depth of the pavilion could be successfully reduced to a fraction of the height of the crown—if, for instance, the pavilion were heavily flawed—but I have never found a pyramidal diamond with an entirely flat base. Such a diamond would show no reflection whatsoever.

One good example is the gem on the horse’s forehead in the statuette of St George in Munich. A detailed examination of the stone revealed that it had crown angles of 45º and pavilion angles of 10º. The ‘size’ of the Point Cut is 14 x 14mm. The overall height is about 10mm and it weighs about 10 ct. These figures indicate that it was fashioned from a rather inferior octahedron.