Faceted Gemstones

Faceting Gemstones

The average person viewing a faceted diamond or colored gemstone will be amazed at the complexity of design and the amount of work and patience it must have required to produce such a stunningly beautiful product.

Faceting is the art of cutting facets, or flat faces, on the geometric shapes of precious and semi-precious gemstones. Faceting improves the appearance of gemstones by facilitating and enhancing their ability to reflect light, creating a dazzling and brilliant sparkling effect.

History of faceting gemstones

A primitive form of faceting appeared as early as 3000 B.C.E., when cylinders made of serpentine were commonplace. A remarkable amount and variety of seals from the early Bronze Age in ancient Mesopotamia have been uncovered by modern archaeologists. These seals were often worn as amulets, and are thought to have expressed the individuality and unique characteristics of the wearer.

Some of the most popular transparent gemstones, including ruby,
emerald, garnet, and sapphire, appear in the earliest jewelry from India, Burma, Sri Lanka (contemporary Ceylon), and Persia (contemporary Iran). In the early Islamic period, the art of faceting was developed further, and the technique of polyhedral faceting was originated. By the early 13th and 14th centuries in Europe, human technology had advanced to the point that true diamond-cutting became possible. By the 15th century, advances in polishing and symmetry facilitated the rapid development of faceting, and pioneering techniques and cuts (many of which are still used today) came into existence.

Gemstone Cuts and Shapes

There are literally hundreds of different faceting arrangements, but the most common is probably the round brilliant cut, which is frequently used for diamonds and many colored gemstones. Faceting is usually accompanied by polishing, but in certain cuts, some of the facets are left frosted to create unique effects.

Facets are overwhelmingly flat faces, but sometimes advanced gemstone faceters will create fantasy cuts by tunneling small grooves into the surface of the gems, thereby creating an exclusive blend of faceting and intricate carving work. Fantasy cuts, sometimes known as fancy cuts, are sometimes used with asymmetrical gemstones. Popular fantasy cuts include the baguette (bread loaf), marquis or navette (little boat), princess cut (also known as the square brilliant cut), heart-shaped cut, briolette (a form of rose cut), pear-shaped (teardrop), and the trillion, which is triangular in shape.

How is a stone faceted?

The methodology of faceting involves cutting precise angles on the top and bottom of the gemstone because the faceting machine forms a right angle at which the stones angle on the abrasive disk is controlled. The faceting machine uses a motor-driven plate that holds a perfectly flat disk (also known as a lap wheel) that does the actual work of cutting and polishing. The process involves mounting a gemstone onto a dowel (usually a metal rod), also known as a dopstick, and then fitting it into a quill. The quill holds the dopstick in place so that precise angles can be achieved.

The faceter must hold the stone against the turning lap wheel and carefully monitor the progress of cutting the crown, which is the top of the stone, and the pavilion, which is the bottom. The most important things to keep in mind during the process are height, angle, and indexing. Height controls the depth at which the gemstone is cut, angle establishes the plane upon which the stone is cut, and index refers to the precise placement of the facets around the shape or outline of the gem.

Faceted stone or Cabachon?

How should you decide whether to go with a faceted gemstone or one that has been cut en cabochon?

Cabochons are gemstones that have been shaped and polished rather than cut, and are usually used with opaque gems. Much depends on your own unique style and preferences, as both cabochons and faceted stones are strikingly beautiful.

One important thing to keep in mind, however, is that reflected light enhances surface colors and textures. Cabochons rely principally on the light reflected off the surface for their optical performance and to enhance and display the color, texture, and pattern of the mineral. Faceted gemstones, on the other hand, utilize both reflection and deflection. What this means is that the light not only reflects off the surface of the stone, but actually enters the crystal, reflects off the interior angled facets, and then emerges once again. Therefore, the brilliancy and sparkle factor is a major determinant of whether you should go with a cabochon or a faceted gemstone.

Choosing a faceted stone

When analyzing a faceted gemstone, there are a few important questions to ask yourself.

• Do the edges and intersections meet precisely? This is evidence that the facets have been cut uniformly.
• Is the gemstone properly proportioned? Usually, the best proportions for faceted gemstones are when the top part of the stone comprises 1/3 of the total height, with the bottom part comprising the other 2/3.
• Does the gemstone sparkle and shine? This is evidence that proper polishing techniques have been followed.
• Is the gemstone properly positioned in the jewelry or mounted into a display arrangement?
• And finally, what is the optical performance of the gemstone? Ideally, when shifted, the stone will both reflect and refract light from a variety of angles.

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