21. September 2016 06:15 /
Lapidary is the science and art of cutting stone, creating beautiful items of collection from them. It is often used to describe the cutting of gemstones but now used to signify the entire process of gemstone manufacturing, from cutting to polishing and colour enhancements. Here are some important terms every buyer and gemstone collector should know about lapidary.
It is the simplest process of cutting gemstones. It is similar to the action of the river water on the pebbles lying on the bed. Tumbler is an abrasive process, where rough gemstones are put into a tumbling well fitted with abrasives. The rough surface is instantly smoothened without fracturing the gems. Semi-precious rocks are tumbled for high lustre, and preferred because of its low-cost technique. However, it is not recommended for gemstone with hardness less than 5.
It is better known as Cabochon cutting, and remains the best procedure to cut precious gemstones. Diamonds, rubies, emeralds and sapphires before 19th century were cut in the cabochon. How is cabbing done?
Cabochon gemstones are cut with a flat bottom and curved or pyramid/domed top. Cabbing is done to enhance the resale value of the gems, especially opal gemstone and turquoise gemstones. Cabbing is more sophisticated than tumbling.
There are hundreds of gemstone polishing techniques, but cabochon polishing is very unique. It involves the use of aluminium oxide and cerium oxide. Stones that are susceptible to heat treatments are cut and polished in cabochons. Opals and quartz are cut using cerium oxide, while jade is polished using chromium oxide.
Ruby and sapphires are polished using Diamond Polish, fitted on leather pads. It is a costly process.
Faceting, undoubtedly, is the most economical lapidary technique in the list. Most diamonds gemstone and sapphire beads set on engagement rings are cut in facets. Faceting is the cutting of gemstones in polygon, polyhedron, and polytope, without adding any new vertices.
The faceting methodology involves the mounting of the crystal on a metallic dowel/dipstick and then fed to the faceting machine. The faceting machine works on the crystal in two sequences—cutting the Crown, and then Pavilion simultaneously. Lapidary artists work with HAI factors, where H is Height, A is Angle and I is Index.
Faceting quality is established by studying the 5 Ps of analysis—
Next most important gem cutting technique is the carving. All faceted and cabochon cut gems feature disciplined shapes such as domes, ovals, circles, and squares. Carving involves cutting a gemstone in such a way that they reveal peculiar tunnels, inclusions, and channels with deep plateaus and trenches. It is the mother technique associated with modern-day Fantasy cuts.
• Fancy Cabochon Shapes:
Carving of cabochon cut gems gives a fancy feature like Emerald cut, tear drops, ovals, hearts and pears and Marquis cut.
• Cushion Cut:
They are cut and carved in square and rectangular shapes like a cushion. Shield cut, Ceylon cut, Brilliant cut and Barion cut, all owe their existence to the carving techniques.
: Opal Gemstone . Turquoise Gemstone Beads . Sapphire Beads . Diamonds Gemstones