This is a general overview of how to cut a cabochon and contains procedures that are to be followed in this studio. Actual hands-on experience is taught once you have fulfilled eligibility requirements and can use the studio.

Cut a slab

You can avoid needing to use a slab saw by purchasing pre-cut slabs from gem shows or from the studio supply.

1. Automatic slab saw (not located in studio)
   1. Stone is fed into stationary saw blade via screw drive.
   2. No matter the hardness of the stone, it will always take the same amount of time to cut a given thickness.
   3. Authorized for use by the studio master or their designee.
   4. You may bring in limited size rock to have slabs cut for a fee.

Cut a shape

Use gem templates to mark out shape on slab. Use the trim saw to cut slabs into rough shapes for further grinding. Your goal is to trim your piece as close as you can on the trim saw.  The more you can remove by trimming, the less time you must spend grinding.

1. 6″ Trim Saws:
   1. Only for cutting stones that have already been slabbed to no more than 1/2″ thick.
   2. Check coolant level prior to use – DO NOT RUN DRY.
   3. Check the blade for obstructions or damage.
   4. Keep stone flat on cutting table.
   5. Grip both sides of the material firmly, keeping fingers away from blade.
   6. Gently push the material into the revolving blade. Don’t use heavy pressure when cutting.
   7. Make straight line cuts only.
   8. Turn the power off before walking away from the saw.

Refine the shape

The hard diamond wheels are used for removing sharp edges and corners. This MUST be done prior to using any soft resin wheel. At the end of the lower grit wheel, you should have a roughly shaped domed stone with a 12° to 17° bezel all around. After the higher grit wheel, you should have a more smoothly shaped stone without facets or heavy scratches, with all sharp edges removed, leaving only a small amount of material that makes the stone just a fraction too large.

EZ Cab Side View

1. Grinders (Hard Diamond wheels):
   1. RINSE STONES BETWEEN EACH WHEEL.
   2. DO NOT RUN DRY – Make sure the water is turned on.
   3. Make sure enough water flows so all residue flushes from the wheel.
   4. Assure that input lines and drain lines are not plugged.
   5. Use a light to medium pressure with a circular, oscillating motion.
   6. Use the whole wheel – work from side to side. Do NOT ride the center of the wheel and avoid the edge of the wheel.
   7. DO NOT progress to a finer (larger number) grit without first using the prior rougher (smaller number) grits, or you could damage the finer grit wheels.
      1. Create the pre-form – 80 grit wheel.
      2. Create the cabochon shape – 220 grit wheel.
   8. If you lose your stone below wheel, turn off equipment and allow wheels to stop before retrieving.
   9. Turn water off before walking away from wheel.

Smooth/polish the stone

You will now be shaping and smoothing your stone using progressively finer grit with the goal of removing all visible scratches from previous wheels. These wheels have a resin backing that makes them soft for rounding surfaces, consisting of resin embedded with diamond grit. Stone should be smooth before starting this process. Therefore, the stone should have no sharp edges or corners that could puncture/rip the surface.  

You would only need to spend a minute or two on each wheel.

1. Must have cab checked for sharp edges by steward.
2. Place stone on dop stick (a wooden or metal holder used to secure a gemstone in place for grinding and lapping) for better control.
3. Pre-Polishing (diamond resin wheels):
   • RINSE STONES BETWEEN EACH WHEEL.
   • Make sure the water is turned on – DO NOT RUN DRY.
   • Make sure enough water flows so all residue flushes from the wheel.
   • Assure that input lines and drain lines are not plugged.
   • Use a lighter pressure with the circular, oscillating motion when working stones, particularly on these wheels that have a foam cushion beneath the grit. This cushion is to allow minimal pressure to polish surfaces, but too much pressure here can cause damage to both the wheel and the motor.
   • Use the whole wheel – work from side to side. Do NOT ride the center of the wheel and avoid the edge of the wheel.
   • DO NOT progress to a finer (larger number) grit without first using the prior rougher (smaller number) grits or you could damage the finer grit wheels.
   • Proper Polish Sequence:
     • 360 grit wheels
     • 600 grit wheel
     • 1200 grit wheel
     • 3000 grit wheel
   • If you lose your stone below the wheel, turn off equipment and allow wheels to stop before retrieving.
   • Turn water off before walking away from wheel.
4. Flat Polishing Disk
   • Keep your stone in the work zone, from the horizontal center line to just short of a vertical center line.
   • The closer to the center, the less friction, the slower the disk.
   • Use only the flat surface of the disk.
   • Use a firm pressure and a circular oscillation motion.
   • Use appropriate compound with disk:
     • Cerium Oxide: Cerium oxide will polish at a faster rate than conventional polishing compounds and produce a superior optical lens surface with no staining or caking. Because it will polish faster, a lower concentration can be used. It is recommended for use on leather, felt, polyurethane foams, and thermoplastic polishing pads. It is a favored polish for quartz type minerals and other gemstone types. It is not recommended for gemstones that will undercut. Color: Buff/Tan.
     • Tin Oxide: Tin oxide is an excellent general-purpose polish. It is used to provide a final high gloss finish. Color: White.

6. Cloth Buffing Wheel
   1. Keep your stone in the work zone at the front surface of the wheel, from the horizontal center line to just short of a vertical center line.
   2. Do not use the side of the buffing wheel.
   3. The only compound to use with buffing wheel is ZAM.

If, after polishing, you find there are flat spots or scratches, you will need to go back to the appropriate wheel and regrind/polish your stone to correct these errors.

Be courteous, don’t monopolize a single station for more than 30 minutes if people are waiting. It’s a good idea to have several stones in various stages of completion so you can jump in whenever a station opens.