Point cut
from the Antique Jewelry University
The point cut is basically a polished octahedral (eight-sided) diamond crystal. Natural crystals were polished in order to achieve full transparency and symmetry while keeping the loss of weight to a minimum. The first point cuts we have encountered were cut in Venice, Italy, from the first half of the 14th century on.
Natural crystals often have irregularities and are distorted. The early diamond cutters would grind (and brute) material off the stone trying to smooth the crystal faces while attempting to keep the widest area of the stone intact; this becomes the girdle. After all, it's this part of the stone that will determine the 'look' of it's size. A diamond cutter, when handling an octahedral crystal, would have three possible girdles to pick from and would choose the one giving him the largest outline.
From ancient times on the idea lived that a diamond needed to be 'natural and untouched' to maintain the best of it's magical powers. The point cut was a way to bring crooked and flawed crystal towards the ideal: a perfect octahedral crystal, without appearing modelled by man, was the most popular shape of a diamond in those days.
Crystalline materials, like a diamond, display differential hardness; the material's ability to withstand scratching is different in certain directions. A diamond's ability to withstand scratching along it's natural octahedral crystal faces is very high. Therefor the grinding and bruting would have to be done on an angle that diverged at least one or two degrees from the natural angle of about 54.75°.
In order to keep the maximum girdle width the above implies that the stones point's would have to be cut shallower then the natural point. In a natural octahedral shape most of the light falling into the stone gets lost. A dark square, sitting diagonally in the square outline of the gem is the result. Shallower points lead to different appearances of the stone when viewed down the point. The shallower the point, the smaller the dark square. This is illustrated in the image below.
Point cuts were often set with reflective foils behind them to maximize the light return. Apart from the internally reflected light, the diamond's superior lustre (surface reflection) makes it the brilliant gem it is. A high polish of the gems faces is vital to bring a stone's brilliance (internal + external reflection) to it's maximum. The diamond point stood for strength, courage, endurance, fortitude and valour and was worn on finger rings by royals who liked to be associated with those virtues.
Sources Consulted
- Tillander, Herbert. Diamond Cuts in Historic Jewellery 1381-1910. London, England. Art Books International, 1995. ISBN 1874044074
- Gem-A Diploma coursework. The Gemmological Association Of Great Britain, London, England
- Catelle, W.R.. The Diamond. John Lane, The Bodley Head, London, 1911
- Kunz G.F.. The Curious Lore of precious Stones. Philadelphia, USA. J.B. Lippincott Company, 1913. ISBN 0486222276