Lapidary cab rough December 6, 2008 rock sale houston heights
Lapidary cab rough
All rocks have beauty within them. It takes an experienced lapidary to bring it out. A lapidary is someone who takes rough stone, rock, or minerals and cuts and polishes them so that they may be added to jewelry or simply kept for display. Some lapidaries carve stone into fanciful or representational shapes. Others will take materials like agate, onyx or fluorite and shape it into useful items like bowls, vases and plates.
For a lapidary who makes primarily cabochons (a cabochon, or cab, is flat on the back side and either domed or slightly domed on the top with a high polish), it all begins with saws. Actually, it all begins with the rock. However, we are not talking about rock hounding today.
After acquiring a piece of rock, it must be cut into slabs. If the piece of rock is quite large, The Lapidary will have to begin with a slab saw. A slab saw typically consist primarily of a disc shaped blade with a diamond coated rim, a motor, and a reservoir to hold the coolant/lubricant. The coolant/lubricant can be either water or oil. Water is a lot less messy and typically only commercial cutting houses will use oils. The largest slab saw this author has ever seen stands about eight feet tall. It is a diamond blade drag saw and was built to cut large petrified wood stumps.
Depending on the size of the finished cabochon and the material being used, the slabs will be cut to varying thicknesses. If the lapidary wants a very high dome on the finished cabochon, the slab will need to be fairly thick. Also, softer materials produce more waste when cutting and polishing and therefore, need to start out thicker.
A Trim Saw is a smaller version of a slab saw. These are most commonly cooled and lubricated with water. If the rock is small enough, a trim saw may be used in place of a slab saw. Trim saw blades most often are four inches, six inches, eight inches or ten inches in diameter. A four inch diameter blade will slice through a rock that is less than two inches deep.
When the lapidary has the slab that she wants, primarily the trim saw is then used to trim the slab as closely to the finished shape as possible. Some lapidaries produce calibrated shapes. These are usually traced onto the stone with a template. The most common shape found as calibrated cabochons is oval. However, square and round shapes are also produced.
They will be made to a strict set of size requirements. This is usually expressed in millimeters: 12mm x 10mm, 30mm x 20mm, for example. These are primarily made for purposes of competition. They are judged on best use of the material, size, perfection of shape and polish. Most commercially available calibrated cabochons are made by machine and the final polish is achieved in a tumble polisher.
This author finds free-form cabochons to be most pleasing. They also present the biggest challenge for working into jewelry. It is possible to purchase mountings for the calibrated shapes, but not so for the free-form shapes. Mountings for the free-forms must be fabricated from scratch. Your piece of artisan jewelry has had a great deal of time put into it by the time it has found its way to your neck or wrist.
Once the slab has been trimmed to a rough shape, then the real fun begins. The lapidary then grinds and polishes the stone. This is where the lapidary's skill really shines.
