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The complexities of cut
Metrics for beauty
  Metrics for beauty Page 2
  Metrics for beauty Page 3
1. Introduction
2. The complexities of cut
3. Metrics for beauty
      Metrics for beauty   page 2   
      Metrics for beauty   page 3   
4. References
  There is new excitement in the gem-stone industry. Today, for the first time, scientific advances are allowing the detailed optical design, precision cutting and characterization metrology of beautiful jewels. Understanding how to cut a stone to best disperse and break light into a plurality of colorful scintillations has consistently been a major focus of the gemstone industry. Diamonds, for example, are marketed on the basis of the Four Cís: cut, color, clarity and carat weight. Of these four attributes, "cut" is the least understood by the general public and by jewelry industry professionals. The word is used to refer not only to the shape of the diamond but also to its proportions, symmetry and polish. The quality of the cut is primarily responsible for making a stone appear brilliant and colorful, or dull and lifeless. It is obvious that an understanding of how a gem manipulates light to produce the effects of brilliance (brightness), fire (dispersion) and scintillation (sparkle) is critical to the proper design of jewels.

Another important reason to understand the behavior of light in gemstones is to establish and apply grading systems.* Given the large variety of gem materials and shapes available today, grading systems that make use of metrics based on light response and beauty have been introduced. The gem-buying public also benefits from an understanding of light propagation in gemstones. The main focus of this article is to describe the role of optics in gem-stone design along with related trends in the gemstone industry. 

* Professional organizations such as the American Gem Society (AGS) offer their members services that range from certifying the authenticity of gems to giving an expert opinion on quality.

All Optical Society of American journal articles are available at www.osa.org/pub_svc

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