The Girlfriend's Guide to Jewellery
16: Cutting 2011-05-26
The size of a gemstone is described by its measurements. Gemstones are usually measured in millimetres or fractions of millimetres in three directions: width, length and depth. For most of us choosing a gemstone is a visual choice. While we are probably not familiar with the actual carat weight of a sapphire or an amethyst we know what size we like when we see it. The one exception to this approach might be diamonds. Most of us have looked at diamonds and they are almost always shown to us along with a comment regarding their weight, ‘this stone is a half carat’ or ‘this diamond weighs a full carat’. As a result, it is not uncommon to hear someone express the size of diamond they want in terms of its carat weight, ‘I want a one carat diamond’.
The shape of a gemstone is its form or the outline it presents. The shapes we encounter most often include round, oval, pear, cushion, heart, square, emerald, rectangle, triangle, marquise and free form. Some less frequently seen shapes include half moon and kite. Shape does not describe cut.
Cut and Cut
Cut refers to how a gemstone is finished and it is meant to enhance the beauty of the gemstone. There are two basic ways to finish a gemstone. It may be polished or it may be facetted. A stone with an all over polish may be half or fully drilled as a bead and may be presented in a variety of shapes. When a stone is cut and polished in a dome shape with a relatively flat to a flat underside it is called a cabochon cut. Cabochon cut is usually but not exclusively used for opaque to translucent gem material. The underside of a stone cut ‘en cabochon’ may be left unpolished. Faceting is usually but not exclusively used for transparent gem material. When a stone is polished and facetted there are many different patterns of faceting possible. Two of the most frequently used faceting patterns are brilliant cut and step cut. These may be used on a wide range of shapes.
Cut may also refer to more than the manner in which the stone is polished and or facetted. The word ‘cut’ may also be used to describe the proportions, symmetry and polish of an individual gemstone.