The Natural Diamond Point

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

The natural Diamond Point (naif or pointe non faite in early French inventories) is an octahedral crystal with natural faces. The term has been in use at least since the middle of the twelfth century: it can be applied to any natural diamond crystal which, when set, shows a sharp apex or point, but the term is restricted to the natural octahedron. Since this is one of the three fixed forms in the isometric (cubic) crystal system, in theory it always displays exactly similar triangular faces, with fixed angles between the faces and fixed height proportions.

However, perfect symmetry with smooth, shining faces is hardly ever found in diamond crystals. They often have a natural bipyramidal form (either regular or with curved faces and edges) but are more often distorted because of unequal face development. In fact the octahedron frequently occurs in combination with one or both of the other fixed forms—the dodecahedron and the cube. It is also found combined with one or more of the four non-fixed isometric forms. Though absolute perfection is rare in a natural crystal it can, of course, be achieved by cleaving off irregular sections.

The natural Diamond Point was highly valued in ancient India and therefore hardly ever officially exported to the western world—there are, for instance, no pointed diamonds in the illustrations of the stones brought back to France by Jean-Baptiste Tavernier in the seventeenth century. But when it did finally reach Europe, the ‘point’ became a popular symbol and was used for all sorts of purposes, such as interior decoration and the facing of building.

In a natural diamond octahedron, the angle of inclination of the crystal faces at the girdle plane is 54º 44’ 8.3’’, usually rounded up to 53¾º. The sides of each triangular face will meet at a point forming an angle of 70º 31’ 43.4’’ (70½ º). By checking these figures it is possible to verify that a pyramidal shape is a true crystal and not a fashioned bipyramid, in which the angles differ from those of the natural crystal.

Most early Diamond Points were later fashioned into Tables, and later still into Brilliants. Regrettably, very few have survived in their original shape, and those that do are either foiled or their settings filled with dirt so that their beauty is no longer apparent. They are known, however, from museum collections, portraits and descriptions in wills and inventories.