This month’s blog article illustrates a specific type of gem cutting, namely faceting. Next month’s blog article will illustrate the most important gem shapes and cuts. Enjoy the reading of this blog article and stay connected for the next one!
If you can envision a diamond set into an engagement ring, you are looking at a faceted gem. The surface of a faceted gem is covered with several geometrically arranged, flat surfaces. Each of these flat surfaces is called facet. This kind of cuttingis typically reserved for transparent gems, but occasionally, translucent and opaque stones may also be faceted. Gemstones have facets cut into them in order to improve their appearance. Since the quality of the cut is directly responsible for the stone’s beauty, the precision with which the facets are arranged is very important. The facets act as mirrors that allow the maximum amount of light to enter the gem and be reflected back out of the front of the stone to the viewer.
The top of faceted gems is called the crown. The widest part of the gem, which is the part that defines its outline, is called the girdle. Viewed from the side, the girdle is usually fairly thin. The bottom of a faceted gem is called the pavilion. The large, horizontal facet on the top, which is the one that acts as a window into the interior of the gem, is called the table facet. One additional facet, called the culet, is sometimes polished on the base of the pavilion. It is claimed that this is done to protect the point of the pavilion from damage, although it also conveniently disguises any asymmetry at the junction of the pavilion facets. Many faceting styles, including emerald, princess and radiant cut, do not have a culet.
With a colorless transparent stone, one of the main aims is to achieve a polished gem with the highest brilliance. Its brilliance depends on the surface reflectivity or luster of the stone and on the dispersion of white light entering the gem’s crown facets into its spectral colors, producing the effect of fire. This term is used to describe the rainbow-like flashes of color that are commonly seen in diamonds and other gemstones, such as sphene and zircon. Each color represents a wavelength within the spectrum of visible light – red, orange, yellow, green, blue, and violet. Fire is best seen in colorless or lightly colored gems, since deeper, richer colors tend to mask the effect.
With regard to colored gemstones, a cutting style may be chosen which emphasizes or lightens the depth of color viewed through the crown facets.