Faceting machine

The vast majority of jewelry-store gemstones are faceted either abroad in factories or entirely by machines.

There are two major components of a faceting machine: The mast/head assembly, and the grinding wheel, or lap.

The lap, or grinding wheel, is placed onto it rather than a record, and the arbor is machined to run perfectly flat when turning.

The flow of water captures the particles in a slurry, which drains into a rubber container around and below the lap.

Its components are as follows: Mast: A vertical pole mounted into the base of the machine on which the assembly is positioned.

Facets at incorrect angles can mean a gemstone that is lifeless or transparent rather than sparkly.

In order to cut facets around a stone, the quill must be rotated around its long axis.

Height Adjustment: The depth of a facet is determined by how high or low the head assembly is relative to the lap.

Generally the first adjustment will set the rough just touching the lap, so that a very shallow facet will be placed.

The head can then be lowered by a micro-adjustment and the facet can be cut and re-cut until it is of a desired depth.

The head is then grossly adjusted for height so that the rough is just touching the lap when it is lowered into position.

Gentle pressure is applied and the mineral is ground away until the quill reaches the desired angle.

If it is of adequate depth, which generally means the inner side of the facet has reached the midline of the stone, the index is turned to number 8.

Once the basic shape is established, a series of different laps can be used that are of increasingly fine grit.

Diamond is the hardest known substance on earth, so finding a material that can be used to cut it presents a problem.

The process is far more involved and, of course, more expensive, so diamond cutting hobbyists are far rarer than cutters of other gemstones.