Step 1. Marking the stone
The shape of the rough stone and its crystaline growth dictate whether it yields one or more finished stones. To decide upon this, the manufacturer checks the shape and the inclusions. Very often, the surface of the stone is difficult to see through, and then he will give it to a polisher, who will polish 'windows' on the stone. These are small polished surfaces, that permit to look inside the stone and to locate the inclusions.
Then, very often a Sarin with rough-measurement is used to measure the stone, and to see which are the most valuable stones that the piece of rough will yield. The decision is a combination of measurements, location of inclusions, market knowledge and speed of turnover of specific polished diamonds. This decision is often a joint decision of a marker, a sawyer and the manufacturer.
Step 2. Sawing or cleaving
The nicest rough can be sawn in two pieces. More difficult rough can be cleaved in 2 or more pieces, and other rough will get no preparation and will yield just one stone.
In the case of cleaving, a specialist cleaver splits the stones. Nowadays, this action is often replaced by laser-sawing, and then it is another specialist performing the operation.
In the case of sawing, the marker will have put a thin line on the stone, that indicates the sawing-plane. A setter (another specialty) will set the stone in a pot with glue or concrete, and the sawyer will perform the actual sawing operation.
One remark: remember that the first operations are always more important than any of the following. Nobody can repair a mistake of an earlier operation, and the further away from the final result, the more difficult it is to assess the problems.
Step 3. Bruting
To keep it simple, I will stick to round stones and to fine cuts. There might be small differences, depending upon the factory, and also, specific problems within a stone might create a different series of events.
However, generally, the next step is bruting, making the stone round. This is performed by a specialist-bruter. In a first step, we are not going to the final diameter of the stone, but only come close to it.
Step 4. Table polishing
If the stone is not sawn, we are using the round girdle to hold the stone, in order to polish a table on the stone.
Step 5. Blocking
This is performed by a cutter on a cutting-wheel, lately very often with automatic machines. This operation takes away most of the rough material, and since this takes a lot of time, it is often automised. This automation is very important, since we are working on the biggest facets, and the friction creates a very high temperature. A human cutter is bound to try and force this operation, put more weight on the stone, and thus even increase the friction and the temperature, risking to burn the stone or even to have it explode.
After the blocking, the stone will have 8 main facets, both in crown and pavilion. However, these are not the final facets. Their orientation might still change, and for sure, they are cut at a slightly higher angle than the final facets. Blocking is done to take away most of the rough material, and to check whether the finished stone will come out.
Step 6. Table smoothing and/or table tilting
Now, another cutter finishes (smooths) the table and, if necessary will slightly tilt it, because the previous operations show that this is necessary.
Step 7. Final bruting
Back to the bruter, who will put the final girdle.
Step 8. Girdle faceting
Back to a cutter, who will facet the girdle, either by hand, and if it is a sawn stone, possibly with a girdle faceting machine.
Step 9. Pavilion
Then, a cutter will finish the pavilion. Some factories will have two different cutters finish the main facets and the halves, while others will have the pavilion finished by one cutter.
Step 10. Crown
Finally, a cutter will finish the crown facets. Also here, one or two cutters might be involved.
Summary. As you can see, cutting involves many operations, and I have only explained the most straightforward one. How many persons are actually working on the stone depends highly on the organisation of the factory, but it is definitely teamwork. Also, keep in mind, that a stone returns regularly to the owner-manufacturer, while in process, in order to check the process, and to possibly adapt earlier decisions on the goal.
If all operations would start immediately after the previous one, it is possible to finish a stone even in one day, I would think, but factory organisation increases the time easily to two weeks and more.
I hope that this info was useful.
Live long,
Paul
