Basic Lapidary Arts | CRATEX Abrasives

In this chapter we’ll introduce the four basic lapidary art forms: tumbling, cabbing, faceting and carving.

Rock Tumbling

Tumbling is the simplest form of lapidary, as it requires minimal equipment. The equipment is not expensive and tumbled stones make wonderful homemade gifts. To tumble rocks, you’re going to need: rocks of similar hardness (hard rocks will eat up your soft rocks, so keep them similar!), a plastic or a rubber-lined barrel, abrasive grit (silicon carbide is used most often) and a liquid lubricant (universal lubricant is water).

The barrel is then loaded with rocks, abrasive grit and lubricant, and placed on slowly rotating rails. The appropriate rotating speed depends on the materials and the size of the barrel. The process reminds of the natural process of creating sea glass - as the barrel rotates, the rocks will slide past each other with the abrasive grit between them, which will cause smoothing and polishing of rough surfaces. Watch your rocks turn for a few minutes to see if more water is necessary or not.

The full process usually takes three to five weeks and it depends on the hardness of the rocks and the shape that you want to achieve by the coarser grits, so it is important to check your rocks daily for desired shape and smoothness.

Tumbling starts with coarser grits, after which progressively finer grades are used with washing between switching grades. You’ll need to clean your barrel well before the next step, as any grit left from the coarse tumble will possibly reintroduce scratches into your piece.

Polishing is the last phase and it involves the usage of powered polish, water and small plastic pellets that have cushioning effect. 

Besides the barrel tumblers (rotating tumblers) there are also vibratory tumblers with vibrating rather than rotating barrels. Although barrel tumblers are more common, mostly because they are less expensive, simpler and quieter, there are some situations where vibratory tumblers are a better choice. For example, you should use them when making tear drop forms and faceted shaper, because they will retain the overall shape of the rock (barrel tumblers won’t keep protect the shape of the rocks but will make them round).

Tumbling tip: Add one table spoon of Old Miser into the barrel. It will keep the grit from clumping together and give you a tumbling slurry almost immediately. By holding the grit to the stone, it will speed up the process and save the grit.

Cabbing

Cabochon cutting, or cabbing is the most common lapidary art. Even if a person is not familiar with the name, we’ve all seen jewelry gems that have a flat bottom and a curved or domed top. These are called cabochons.

The cabbing equipment is much more serious (therefore expensive) than the tumbling equipment, so it can be quite a profitable hobby. In case you use gems that you find yourself, it can be even more rewarding.

Unlike tumbling, which can be an amazing pastime activity for the whole family, cabbing is more complex, as you’ll need to go through the whole process of shaping stones with your own two hands.

 

Faceting

This is the art form that has most potential to acquire profit. Everyone knows what a faceted gem is, they are only not aware of the term. Just think of an engagement ring diamond. Familiar now?

Flat, geometrically arranged surfaces that cover the surface of the gem are called gem facets. The purpose of the bottom facets is to reflect the light that is falling through the stone and to reflect it back, which makes the stone shinny and brilliant.

Faceting is performed on different kinds of faceting machines, and whether you want to take up this type of art as a hobby or to make a profit, you’ll need to make serious investment in the equipment. The quality of your equipment will reflect on the quality of your work, so do some serious research before purchase.

You won’t need an extraordinary artistic sense for the art, just check out all those machinists, engineers and other math buffs exceling at it.

Gemstone Carving

This is the most challenging form of lapidary art, and unlike cabbing, you’ll need to have a highly developed sense for it.

Gem carving is usually performed on sea shells and agates, but almost any material will do, including cabs. The cutting of the top of the cab is called intaglio (“relief carving”), and of the back - reverse intaglio.

Carvings are not found only on jewelry pieces, but on other pieces that can be turned into and sold as beautiful works of art.