GemDiagram Docs

Cutting Assistant: At the Machine

You're now at the faceting machine with your rough mounted and Cutting Assistant open on a nearby screen or tablet.

Setting up for each tier

For each tier, Cutting Assistant shows the angle and distance. You need to:

  1. Adjust the cutting head: Most machines have an angle dial (0–90°) and sometimes a height/distance adjustment. Set the angle to match the tier.
  2. Check the dop angle: Your stone may need to be rotated on the dop to match the next index position. Reference marks on your dop (or your muscle memory) help here.
  3. Approach the wheel: Touch the facet plane gently to the wheel to verify you're cutting at the right angle — you'll feel if it's wrong immediately.

Cutting the facet

Once the angle and distance are set:

  1. Apply light pressure: Faceting laps are delicate — pressing hard may shatter the stone. Let the lap do the work.
  2. Watch the facet develop: You'll see a small, flat facet grow under the lap. It should be uniform in size and shape (no scratches or irregular edges).
  3. Cut until you hit the girdle or neighboring facets: The facet is done when it meets the edges of the neighboring facets cleanly, with no gaps or overlaps.

Progress tracking

Each time you mark a facet done in Cutting Assistant:

  • The gear diagram updates to show your progress.
  • The facet count ticks down (e.g., "3 of 8" becomes "4 of 8").
  • You move on to the next index position.

Facet symmetry

Because of the symmetry you set in the Developer, many facets will look identical. Your job is to cut each position in order, even though many are repeats of the same shape. The symmetry ensures they all look right once you're done.

Common issues

  • Facets too big or small: You've set the distance wrong. Adjust it and re-cut.
  • Facet doesn't align with neighbors: Your angle is off, or you're on the wrong index position. Double-check the tier and position in Cutting Assistant.
  • Stone is getting hot: You're pressing too hard or the lap is too fast. Back off and let the lap do the work.
  • Lost track of where you are: Pause, open Cutting Assistant, and find your current tier/facet in the gear diagram. Mark facets you've already done and pick up from there.

Finishing

Once you've cut and polished all tiers and all facets, you're done. Clean the stone, inspect it under light, and celebrate — you've successfully cut a gemstone.

See Export a PDF Cutting Report for how to document your finished stone.