| Rough diamonds come in several basic shapes. | | | | |
| The most common shape is in the form known as | | | | There is no definite form which will totally |
| an octahedron. The octahedron resembles two | | | | reflect light falling upon it from every |
| Egyptian pyramids placed base to base, that | | | | direction equally. From trial and error and |
| is the usual crystal form of a diamond. A | | | | experience, cutters make shapes that give |
| rough diamond is rarely found in the perfect | | | | maximum possible effect for light that enters |
| octahedral shape. Another rough shape found, | | | | the stone from the front. Cutting the stone |
| especially in Brazil, is the cube. Often | | | | only a few degrees different from the angles |
| times the rough diamonds shape is a bit | | | | of the ideal shape, results in a decrease or |
| distorted, or have lost edges or edges have | | | | increase of the brilliancy of the stone, and |
| failed to develop. Diamond cutters will have | | | | hence the value. |
| to deal with very irregular shapes at times. | | | | |
| The history of improving the appearance of | | | | To obtain total reflection of light within |
| the rough diamond is exceedingly interesting. | | | | the brilliant, the back of the stone must be |
| The earlier facetted stones were usually very | | | | cut so that no considerable amount of light |
| similar in shape to the rough piece from | | | | should strike it more steeply than 24 degrees |
| which they came. In the past only when a | | | | from a perpendicular to the surface at the |
| defect had to be covered up did the cutter | | | | point where the light strikes. Anybody with |
| apply lots of facets. | | | | knowledge in geometry and trigonometry can |
| | | | calculate what angle the back should have, |
| The methods of the diamond cutter has not | | | | after an angle has been chosen for the top. |
| changed much over the years, but the shape of | | | | Some good angles for a diamond are 35 degrees |
| the finished product has. The ancient rubbing | | | | for the top and 41 degrees for the back. |
| together of stones by hand is very rarely | | | | Angles cut more or less will most likely lead |
| done. Another way to diamond cut is by | | | | to less light being reflected, equaling a far |
| attaching one of the stones in wax as a | | | | less brilliant piece. |
| handle, while the other is rotated at a | | | | |
| moderate speed in a specially constructed | | | | Although poorly cut stones are less brilliant |
| lathe type machine. The facets are sometimes | | | | than well cut stones, the market is full of |
| polished in the same manner. | | | | lumpy stones. There are many reasons for |
| | | | these so called lumpy stones. Diamonds are |
| The object of the slow laborious process of | | | | sold by weight and have been going up in |
| cutting and polishing the rough stones is to | | | | price over the years. Anything that will |
| obtain as much of a total reflection of light | | | | allow a dealer to quote a lower price per |
| as possible, used to dazzle the beholder. A | | | | carat makes sales easier. A smaller nicer |
| very popular cut is the round brilliant. The | | | | diamond will cost more per carat than a |
| brilliant serves to refract and reflect the | | | | larger less finished one. Not only will a |
| light that falls upon it, which also takes | | | | larger stone weigh more, but it will also be |
| place dispersion of white light into | | | | less labor intensive. To the average buyer, |
| prismatic colors. Rarely does a cut reduce | | | | price per carat is what is compared, so it |
| the carat weight of the stone more then fifty | | | | makes sense for dealers to carry some large |
| per cent. | | | | lumpy stones. |