13May The Cutting Edge – Transforming a Stone Into a Gem
After gem material has been successfully mined, washed and sorted, the next stage is usually to cut, or facet, the rough stones. To understand this process, we follow the journey of a piece of quartz once it has been placed in the hands of a skilled gem cutter (also known as a lapidary).
The job of the cutter is to transform the rough stone, which often looks quite unremarkable, into an object of beauty. For larger pieces particularly, this can begin by using a saw to trim the rough piece into a more manageable size and shape, or to remove damaged (or included) parts of the stone.
However, with our quartz, no sawing is required, as it already has a natural pear or teardrop shape and the cutter is able to use that as a basis for the next step, which is called preforming or grinding. This involves the cutter using a machine with wheels embedded with diamond to give the rough quartz the approximate shape to which it is best suited. The fast-moving grinding wheels are cooled constantly with water.
Following the preforming, the cutter uses wheels with finer abrasives for the sanding stage. These wheels allow for more control over the shape of the quartz, as they only remove the tiniest amounts of material on each brief touch.
Once the cutter is satisfied that the shape of the stone is correct, it is time to flatten the gem’s surfaces into facets. The faceting machine usually has a calibrated handpiece to which the stone is attached. This gives the cutter precise control over the angle at which the gemstone touches the faceting wheel. Great care must be taken with the angles of the facets to maximise the sparkle (or fire) of the gem and to avoid creating “windows” (where light passes straight through the stone rather than being reflected back out of the top table facet).
Lastly, the stone is given to the polisher, who uses very fine abrasives to create the surface lustre and complete the incredible transformation of our humble quartz into an amazing gemstone!