Director, Partner at Multicolour Gems Ltd (www.multicolour.com)
The cut is what gives a gemstone its beauty and brilliance. An ideal cut which reflects all the light in an even pattern without any darkness or windowing is always preferable when rough of a suitable shape and clarity is available. In faceted stones, specific indices and critical angles are what produce the maximum brilliance.
The proportions and angulations for diamonds are well known and an ideally proportioned diamond is always desirable. Diamonds are relatively clean and their natural habit is generally ideal for cutting round brilliants to ideal proportions.
Colored stones are a different story. They are normally not clean and their shapes can be blocky, rounded, angular, tabular, elongated or flat. And, because color is the most important factor affecting their valuation, the color needs to be carefully considered in any kind of decisions concerning the cut.
(Aquamarine weighing 1.40 cts and Spinel weighing 1.46 cts from Tunduru,
Tanzania cut into a fancy lip shape from Multicolour.com)
Modern faceting equipment makes it relatively easy to cut a colored stone to ideal proportions with the correct critical angles. Faceting diagrams with the angles and indices are readily available and any dedicated hobbyist will be able to cut perfectly proportioned stones in a short time if they are working with inexpensive materials and are not concerned about yield.
However, since color, clarity, and carat weight are at least as important as cut, every colored stone cannot be cut to ideal proportions. Some rough is very flat, some is heavily included, some is dark, and some is light. Dark stones cut to perfect proportions may increase in value because stones always become lighter as their size is reduced. Conversely, light stones can easily lose value when they are cut down because their color will become lighter. Flat stones cut to perfect proportions will yield tiny stones that will be worth less than if they remained flat and windowed. Heavily included stones should be cut en cabochon, and over dark stones may look even better with a window to lighten their body color.
Inexpensive stones can always be ideally cut and the quality of the cut will add value to the stone. With a low value and plenty of availability on the supply side, the final weights and sizes of the less expensive gemstones are not critical.
(Pair of Tanzanian emeralds weighing 3.75 cts cut into a drop shape from Multicolour.com)
For the rare and expensive gem materials the situation is completely different and the final weights and sizes of the stones are a critical part of their valuation. Valuable gemstones cannot simply be ground to perfect angulations with out the considerations of color, size, weight, and the locations of the inclusions. In many cases the less than ideal cut will be worth more than the same stone cut perfectly because of its larger size.
Native cut is normally a condescending term used to describe poorly proportioned gemstones. The implication is that natives living in the jungle or near the source are unable to cut stones properly. This may or may not be the case but some of these cutters may have a lifetime of expertise and they are well aware of what they are doing. The truth of the matter is, wholesale gemstones prices are based on their price per carat. These cutters sell wholesale to dealers and they want to maximize the weights for their market. They have no market for end users and it would useless for them to cut to ideal proportions and angles because their customers would not pay for the associated increase in price and they would be losing money.
Perhaps a better description would be the “first cut”. The first cut is like a rough draft. And in the case of more expensive materials, they should be cut roughly the first time to get a better idea of their color and the clarity. In fact some of the very people that complain about native cuts are hobbyist cutters/resellers who love to buy them because they can easily foresee what they can achieve by re cutting them. Good cutting is the process of cutting a stone from the rough to the end product and there can be a whole series of cuts in that process. There is absolutely no advantage to cutting a stone perfectly on the first try.
Companies that process quantities of valuable rough incentivize the cutters by paying them per carat. The cutters don’t really care because they are not the owners of the material. However, when they are paid for producing the largest possible stones, they will pay attention and do just that. After that, the finished stones can be re selected for better cutting or calibration or special cuts. There is no other way to control the large scale production of valuable or even relatively valuable gemstone materials. Weight doesn’t really matter for soft and abundant stones like Amethyst, Citrine, and Topaz, but yield is critical for valuable stones like Rubies, Sapphires, Alexandrites, Tsavorites, and Emeralds.
For wholesalers and gemstone manufacturers, a compromise between weight and ideal proportions is the best solution. Some people want a large flat stone that will look big in the ring but cost less while other customers would prefer a small stone for the same price with perfect proportions and angles. And, as most gemstones are included to some degree there is no simple easy rule for every stone. Many successful wholesalers prefer to offer stones in a nearly finished stage so they still have an option to recut, repolish, reshape, calibrate or to cut perfectly for their intended market. Once the stone is cut and reduced in size, it can never be sized up again. There is no undo button!
As a first step, large and valuable stones like sapphires, rubies, and emeralds are always cut for weight. In small melee sizes, these stones can be precision cut because the rough is less valuable. However, as the sizes and weights of the stones increase, the valuations of the stones become primarily linked to their weight, color, and clarity.
Fancy and precision cuts
These kinds of cuts can look great and may maximize the brilliance. Some of the styles are creative but most are just variations of established cutting patterns. Although, there are some exceptions, the cuts are primarily used for less expensive gemstone materials to add value. When sellers mention “designer cut” or “precision cut” to the description of their product, it adds a great deal of interest but these cuts are rarely applied to valuable materials because conventional cuts are more accepted. Designer cuts of soft stones like Amethyst, Citrine, or crystal Quartz or common stones like Topaz do not add any resale value to them. These gemstones may look great but with a lower hardness or no foreseeable rarity, they will never have any resale value.
Nowadays, customers can choose between perfectly cut smaller stones or larger or even much larger stones for the same price. When asked, many customers will prefer the perfectly cut smaller stones but when its time to actually buy, more will go for the larger stones at the same price. Opinions and tastes will vary and the ability of the cutter is evident in the finished product but size, clarity, and color are at least as important as the cut.
Cutting colored stones is an art. Computer programs can analyze diamond rough and offer the best possible orientation and yield but colored stone cutting is complicated in other ways. Because of the colors, the pleochroism, and the orientation, diamonds rules will not work and perfect ideal cutting is simply uneconomical for many of the more valuable colored stones because their final size is as at least as critical as their cut. The cut is the only gemstone parameter that can be fixed so a less than perfect cut is not the end of the story and it can still be easily rectified by an experienced lapidary.
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