DIAMOND CUTTING PROCESS
Of all the diamonds that are found, only half are “gem” quality. The other half are used as industrial diamond. Diamond cutters turn those 50% of gem quality rough stones into sparkling diamonds., a job that obviously requires a lot of professional skill and precision. Every little slip or mistake can turn out to be a quite expensive one. With tools we have today, it is possible to polish diamonds more and more precisely. But the process of cutting diamonds is still based on 4 techniques, used one after the other, that have been known for a long time: Cleaving, sawing, bruting and polishing.
The very first step consists of studying a rough diamond in great detail which is a task for a rough diamond specialist and a marker. He looks at rough stones and determines how the stone can be cut at its best. He takes into consideration the structure of the stone and its impurities that are still in it. He chooses, for example, to make two little stones out of one big one, It is very important that he cuts a diamond in such a way that there is as little lost as possible. Eventually, the rough diamond specialist literally marks the diamond.
The first and the oldest form of diamond cutting is called cleaving. Up until Dark Ages, this was the only technique. The Indians, Greeks and Romans used the to stud their crowns with (nearly) rough diamonds. In spite of that they knew the principal aid to cutting diamond was … diamond!
Cleaving gives the diamond its first shape. All irregularities of the crystal and impurities are removed at this stage. Sometimes that means a cleaver needs to divide the stones into two or more pieces, naturally being careful not to lose any of the good stone.
Cleaving diamonds is craftsmanship. The diamond is fixed in the rod with fast drying cement. Then the cleaver takes another sharp diamond and uses it to nick the the first diamond.
Before diamonds are polished ,most of them pay a visit to the bruter. A diamond will receive its first real shape when bruted. (rounded off against another diamond)
The girdle is created – that is, the surface that marks the border between the upper section (crown) and the lower section (pavilion) of the diamond. The bruter turns the girdle into a perfect circle. He also tries to get rid of any remaining damage left by the rough diamond surface features and at the same time limit the loss of the carat weight. The process has been automated by the machines. Two diamonds revolve in opposite directions and this brutes (rounds) the girdle.
SAWING THE DIAMOND
Sawing the diamond is exactly what the word implies: simply that the stone is divided into two pieces. But of course this is not done in haphazard way. The sawyer studies the stone and decided what method he or she should use. Otherwise, two or more pieces can be sewn for all to be rendered useless. You can compare the process to the carpenter who has to take into consideration the piece of furniture he is going to make before he saws the board.
When diamond is sawn, the stone first needs to be positioned: a stone is fixed in the dop (holder). The diamond cutter mounts the dop on a sawing machine. The saw itself is an extra thin blade coated with the mixture of oil and diamond powder. The rotational velocity of the sawing disk is on average 15000 revolutions per minute.
Sawing is a very slow process, 2mm per hour maximum. It can take days or weeks before large stone is sawn. Just imagine how slow it used to be in the past, when diamond was sawn with the iron and copper wires coated with diamond powder. A job for a very patient and meticulous craftsmen.
In recent years lasers are being used more often for sawing diamonds, which of course are alot faster.
Before stones are polished, most of them pay a visit to the bruter. A diamond will receive its first real shape when bruted. The GIRDLE is created – that is, the surface that marks the border between the top and the bottom of the diamond. Crown (top) and pavillion (bottom). The bruter turns the girdle into the perfect circle. He or she also try to get rid of any remaining rough crystal surface damage that migh still be visible or present on the diamond.
Today bruters hav the machine called “super Bruter” at their disposal. These machines look like like a double lathe .
Two diamonds, also fixed in dops, revolve in opposite directions and go at each others surfaces. This “brutes” (rounds) the girdle. There for creating the basis of the most recognizable and desired diamond shape. The round brilliant cut.
This is the last stage in the diamond cutting process: after this process the diamond finally gets its final shape and brilliance. Polishing is creation of small planes on the diamond, which are called FACETS. This is done in two phases. Firstly, 4 facets are polished on the upper part (the crown) and the lower part (the pavillion) of the diamond. The result is what we call the “cross work”. It can be said that the diamond is briallianteered. That means extremely accurate polishing of the other facets on the ribs of the cross work. To give the diamond its sparkle each facet needs to be polished at the right angle. To do that, the polisher uses a horizontal whirling disc, treated with oil and diamond dust. There are special tongs with adjustable dops that make it possible to position the diamond at different angles on the disc.
Polishers sometimes work on 5 diamonds at once, alot of care and concentration must be therefore applied to the process. If at any point to much is polished at the wrong angle, the diamond will loose its brilliance, value and will risk becoming lifeless and dull. Expert gemologists will notice straight away if the diamond has been polished correctly.
When cutting diamonds, centuries old techniques and modern technology go hand in hand. Diamond cutters are therefore experts on both levels. There are a few schools in Antwerp, Israel and India where one can learn the profession. But this is a job more that any other where you have to be BRILLIANT yourself!