In the Studio – Moss Agate Cabochon

So I’ve been working on quite a few projects over the last several weeks. Most notably I have been working on new guitar picks and more cabochons. I will be posting them as I finish them. Here is one of the cabochons I’ve been working on.

This particular piece is Moss Agate, a very sturdy material. Cutting Agate stones, regardless of the particular type, always requires a bit of a heavier hand. The material is very hard, usually ranging from 6.5 – 7.0 Mohs. This makes for a stone that requires a wheel with a lower grit to start out with.

In this particular case we began with a 60 grit diamond wheel. On this wheel we just cut the stone to our general shape we were hoping to achieve. It allowed us the opportunity to cut the most material in the shortest time possible. The downside to using such a low grit is that scratches can cut deep, depending on how heavy-handed you are. Another potential drawback is that the chance for chipping, or even the whole stone cracking does increase while using this aggressive of a wheel.

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A tip to minimize this is to do a 45 degree reverse cut on sides of the stone, not much just a little it helps to reduce the flaking that can occur on any stone while cutting. This does have the potential to occur during the process of creating the girdle for the stone.

As with all the cabochons we work on after we get the general shape down, we begin our progressions on a slightly less aggressive wheel. For the Moss Agate that would be a 100 grit wheel, for softer material like opal I would recommend a 220 or 280 to start.

We continue the process, meticulously working on the girdle, ensuring a nice couple mm thick girdle. The girdle is the most important step in the process. Everything else is a continuation of the girdle.

After the girdle is complete we begin our progressions, performing angled cuts from the girdle, traditionally I start small and progress anywhere to 45 degrees and up. This is dependent on how thick your cabochon is, thinner and your angles are more extreme, thicker and you can do a gradual curve from the girdle to give you more of a rounded out section.

The back part of the cabochon we start of on the 100 grit wheel to make it as flat as possible, keep in mind that these cabbing wheels are round, and getting a completely flat surface utilizing them isn’t always the easiest process. I actually utilize a flat lap when I need to ensure a nice flat surface on the back of the cabochon.

At this point the progressions on the stone, is nice and smooth, a little on the back, ensure the girdle is still even and polish, followed by an angled curving motion as you work up from the girdle to the top of the stone. Finally a curving polish motion on the top of the stone as you ensure an even polish throughout the stone.

We continue this same process through the 100, to the 220, then the 600 and up to the 1200 grit wheel. The higher the grit goes, the less aggressive the cut will be. It allows you to perform more of a polish, and gradual cut on the stone. Here is a good point to double-check for any flat spots, or uneven cuts. If any are noticed you would go back down and continue your progressions on the harder, lower grit wheels.

The 3,000 wheel is a very soft wheel compared to the 100 thru 1200 wheels. It allows you to be more forceful on certain point of the progression, but not result in too much in the form of excess material cuts.

Traditionally I spend the most time on the 100 wheel, the 600 wheel and the 3,000 wheel. Once I feel that I’ve accomplished all I can on those wheels I will jump it to a 14,000 grit wheel, for a very fine-cut. This grit will allow you to really work on the polish of the stone. We then transition to the 50,000 grit wheel for even more work on the polish.

Depending on the material we are cutting we can then go for a little more on the polish by using a leather pad, or foam pad and some cerium oxide compound. This allows for an even more magnificent shine on the stone.

Be warned though, it can magnify imperfections in your cuts.

So what does everyone think so far of our Moss Agate Cabochon? Sound off down below, and don’t forget to visit our store at for access to a large selection of cabochons, jewelry, crystals, gemstones and guitar picks. I would check back frequently though, the cabochons and picks go quickly.