Blog Details

Cabochon Gemstones

Talking about gemstones, a Cabochon is a gemstone that is cut with a highly polished rounded or convex top with no faceting, with a straight or a little domed base. It may be cut in any shape but normally oval shape is preferred. The term comes from the French word "caboche", meaning knob or small dome. In the gemstone world you will often hear the term cabochon shortened to "cab."

A cabochon is sometimes spelt as cabouchon or sometimes referred as just a cab. And sometimes it is incorrectly spelt as cabochan. So what is basically a cabochon?

Cabochon is a gemstone that has been shaped and polished but not facetted. Nowadays, it is also found in other materials like cat's eye (optic fibre) and polymer clay. It also refers to a method of cutting, mainly cutting a bead or gemstone with a convex, polished, rounded surface without any facets. It also normally has a flat and straight bottom. Faceting is normally applied to transparent stones, most particular, diamonds. In fact, opaque, asteriated, iridescent, opalescent, or chatoyant stones are very suited to having an "en cabochon" cut as the cut brings out the inevitable features of these types of stones. The stones that fall into this category include garnet, jasper, bloodstone, moonstone, cat's eye, star ruby, and sapphire.

Cabochon, especially with cat's eye, highlights the star or eye of the fibre optic bead; which would not be visible in a facetted cut. Normally the back of a cabochon cut gemstone is flat, but with some other gemstones, it may be cored out to lighten the colour. The bottom is either polished or sanded. A flat back makes working and setting the stone easy.

Although the cabochon form of cutting is widely used for opaque and semitransparent stones, but it is also very frequently used for transparent materials that contain too many inclusion to render a good facetted stone. Its colouring and patterning provide the major interest in such stones. This form of cutting is simple but it can totally change the look of a piece of rock, bringing out the illusion of unique patterns and lines in the rock.

Cabochon’s most commonly used shape is oval but it can further come in a variety of shapes like ovals, rounds, teardrops, diamonds, squares etc. Some of the jewellers cut their cabochons in maverick shapes which are designed to showcase specified features of the individual rocks. The cut may also vary in size from a small one to very large one depending upon the purpose or requirement. A rock which has been cut into a cabochon may be described as en cabochon, or it may just be called a cabochon.

Cabochons are also cut in an ellipse shape. This is because the eye is less sensitive to small imbalances in an ellipse as compared to a uniformly round shape, such as a circle. And this elliptical shape, combined with the dome, is attractive.

How to Cut a Gemstone in Cabochon Form?

The procedure to cut gemstone in Cabochon form is simple. First of all just cut a slab of the rough rock with a slab saw, and then print a shape from a template. The slab is then trimmed almost near to the marked area using a diamond blade saw—also called a trim saw. Diamond infused wheels or silicon carbide wheels can be used to grind the rough rock down.

Once the rock is trimmed it can be "doped" or simply completed by hand. "Doping" is normally done by binding the stone with hard wax onto a length of wooden dowel called a "dope stick". The piece is then ground to the template line, the back edges may be bevelled, and finally the top is sanded and polished to a uniform dome.