An index gear is the toothed wheel on a faceting machine that sets each facet's direction around the stone. Each index is one tooth of the gear.
In more detail
Most of our designs use the common 96-tooth gear; a few use 64 or 120. On a 96 gear, the T73's pavilion mains sit every 12 teeth.
How we measure it
Each design on our cut pages names its index gear. Our cutting-file check turns each facet's angle and index into a direction and compares it with the 3D model.
Related terms
- Facet: A facet is one flat, polished face of a cut gemstone. Its angle and its direction around the stone decide where it sends light.
- Tier: A tier is a set of facets cut at the same angle, at several index positions around the stone. A faceting design lists its tiers in cutting order.
- Faceting machine: A faceting machine cuts and polishes a stone one facet at a time. It holds the stone on a dop at a set angle against a flat, spinning lap.
- Cutting-file accuracy: Cutting-file accuracy states how closely a cutting file's facet angles match the 3D model of the same cut. Each cut page gives the largest angle difference and the mean.