The work of lapidaries
The lapidary cuts all stones except the diamond which is reserved for the diamond cutter.
The cutting of fine stones is faster but above all much more varied in terms of colors, shapes and methods. The lapidary creates creations from raw stones or repairs worn stones.
Preparing the draft
The preparation of the stone is done with a diamond saw or freehand on a diamond disc with a coarse grain, to form a blank which must have a shape close to that of the finished stone. Generally, the color is not distributed evenly in the stone, so you must choose one of the shades to present. To do this, the lapidary must place the stone. He must ensure that the table of the stone is perpendicular to the direction where the best color appears, while choosing the side where the least impurities appear. The goal is to obtain the largest stone possible while having the best possible color and luster.
Shaping or preforming
This is the step which aims to give the final shape of the lamination (or girdle) of the stone with the preforming pile. At this time, the stone is already cemented on the stick with wax and the mechanical case is used for the symmetries.
Size
The cutting is done with the mechanical case placed on the evention, in this way the lapidary can obtain all the possible angles between the stone and the disc and thus make all the shapes of stones. It is done with a grain ranging from 600 to 3000.
There are a large number of shapes of cut stones. The most common are the brilliant cut (faceted cut), the emerald cut (stepped, or with cut sides), and cabochons.
polishing
The stone is then polished, this is the last step of the operation to restore the shine of the stone. We generally use a tin wheel and 14-grit diamond powder (sometimes 000). For corundum, a harder mineral, a copper wheel is used.
The repairs
There are two types of repairs: recutting and repolishing.
Recutting occurs when the stone is not the right size for setting, or when the stone is too damaged to only be repolished. Recutting can increase the value of the stone: either by removing impurities or by improving the luster of the stone. However, it causes a loss of weight in the final stone.
Repolishing is done on stones whose polishing is damaged. It restores all the shine to a stone but does not cause weight loss.