SETTING IRREGULAR SHAPED OR FANCY CUT STONES
I would like to write a few words about setting baroque or irregular shaped stones such as opals, boulder opals, turquoise and fire agate. These stones are often cut in irregular shapes to maximize colour and size or to eliminate imperfections. The shapes do not fit standardized settings and the jeweler must face the task of setting difficult and uncomfortably hard to mount stones. They require individual bezel settings often combined with fabricated prongs to secure the semiprecious stones in jewellery.
Jewellers are often discouraged about setting gems, such as opal or fire agate, which requires bending metal around fragile (opal) soft edges (turquoise) or around botryoidal negative contours (fire agate). The many trial and error attempts to get the right curve of a bezel around a stone can result in accidentally scoring, scratching or cracking the edges or points of the stone (opal) and can even stress and break the durable edges of fire agate. It can be done free hand with a strip of metal (carefully shaping around the stone) but my suggestion or answer to this is to make an individualized mandrel for each uniquely shaped gem.
With a simple, even crude mandrel all heavy work can be done away from the stone and only small touch ups of the bezel curves are needed to provide a proper fit. As a material for the mandrel, hardwood is my preferred choice but any hard plastic or phenolic will do. Some wood working equipment like a sander would be helpful but simple hand tools such as files and sandpaper are sufficient with a little help from wood burs on a flex shaft.
For this article I used an old oak broom handle - the wood is tough and just the right size for most projects. The opal I was setting fit perfectly on my first try. Often I have to make a mandrel that is longer and more graduated to stretch the bezel to the right size. I use a strip of paper to determine the length of the metal to be cut for the bezel (measure the outside perimeter of stone). I used sterling silver but fine silver or 18K is much easier to work with. The measured strip of metal is then bent around the mandrel using standard smithing procedures of hammering, bending, filing and soldering to form the shape of the bezel. This method can be refined by each craftsman to suit their own styles.
I use to construct free hand my bezels but now I find this technique is saving me lots of time and frustration on setting free form fire agates. You can see some more examples of my work on my website: www.fireagateartstudio.com or in my show room at the Pueblo Gem and Mineral Show at the Riverpark Inn, Room 151.