Polishing Gemstones

A gemstone gets polished to bring out the lustre and beauty inherent in the stone.

Softer opaque stones are simply polished to create a smooth rounded surface. Stones like this are called cabochons.

A cabochon is created as follows.

 

Firstly the rock is sawn into thin slices.

A round or pear shaped template is drawn onto a partucilarly pleasing area of one of the slices.

This is then cut out using a saw and then the edges are ground down to get the desired shape.

Finally the surface is rounded on a grinding wheel and then polished to finish the cabachon.

Harder gemstones are cut to let light bounce around and through their translucent structure.

The basic techniques of polishing stones are best discovered by getting a lapidary tumbler and having a go yourself. This is something even kids can do safely.

A tumbler basically consists of nothing more than a storage jar

The stones are placed in a tumbler with coarse silicon carbide dust and water and left to tumble around for however long it takes. After a time the silicon carbide is replaced with finer powder grades and a final polish with cerium oxide dust.

Since this process can take weeks it would be next to impossible to tumble polish rocks by hand. Instead a small motor attached to rollers is used to create a cradle in which to tumble the rocks. These tables can be handmade or bought as preassembled lapidry kits.