Glossary of Faceting Terms and Definitions


This compilation of faceting terms and definitions has been generously provided by International Gem Society (IGS) member Tom Mitchell.  He is the author of Faceting 1, Learn The Fine Art of Gem Faceting, it’s Easy.

Acetone

A solvent that can be used to dissolve dop wax or help to release super glue.

Alignment

Positioning the stone so that the crown break facets match up with the pavilion break facets at the girdle after transferring the stone.

Analog vs Digital Angle Scales

Some newer faceting machines have digital angle scales that allow the quill to be adjusted to a 100th of a degree, which corresponds with modern gem designs produced in typical GemCad format. The average machine has a protractor or analog angle dial which reads to 1 degree with a vernier scale which allows further adjustment to a 10th of a degree.

Axis

This refers to 1) the direction of crystal growth in gem material, such as the A-axis or width, the B-axis or depth and the C-axis or length. In some tourmalines the C-axis may be blocked, also referred to as “closed,” which prevents light from passing through it, or; 2) in a symmetrically cut stone, it refers …

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