Colored Stones - A Gem's Pavilion, Girdle and Crown
Gone are the days of standard traditional gemstone cutting. Today's gemstones can be found in every shape, size and cut imaginable. Many gemstone types even have specialized cuts specifically designed to maximized their most desirable traits such as color, fire, brilliance and other optical effects. Evaluating the cutting of a stone requires the understanding of the anatomy of a gemstone. Below is an introduction to some important terminology used to describe the anatomy and cut of a gemstone.
The Gemstone Pavilion
The pavilion is the lower portion of a gemstone that begins just below the 'girdle' (defined below). Pavilions can be cut and faceted in many different styles. Unlike diamond, most colored stones are cut with mixed styles, such as a step-cut pavilion combined with a scissor-cut crown or a coated pavilion with a concave-cut dome. The most popular mixed-cut style for colored stones today, typically combines a brilliant-cut crown with a step-cut pavilion. This style of cut brings out the color of the stone and also maximizes its brilliance and fire. The pavilion of a stone is usually cut with a culet facet. The culet facet is located at the lowest tip of a gem's pavilion. However, not all gemstones are cut with a culet. Many colored stones are cut to form more of an edge rather than a single point - often referred to as the the 'keel line'. When it comes to evaluation and grading, a keel line and a culet are considered to be one and the same.
A culet is intended to help reduce the possibility of cleavage, particularly with gem types that exhibit perfect cleavage. Gems cut without a culet facet can be quite fragile even if they possess a moderate level of hardness. Other colored stones lacking distinct cleavage may still be cut with a culet simply to protect the tip, particularly if they exhibit brittle tenacity. The culet on a gem's pavilion is often described using terms such as "none", "small", "medium" or "large".
Below is a gallery of images showing a small selection of the many different pavilion styles seen today:
|Modified Scissor-Cut Pavilion||Trillion with 'Keel Line'||Step-Cut Pavilion|
|Princess-Cut Pavilion||Modified Round Brilliant||Diamond-Cut Pavilion|
The Gemstone Girdle
The girdle is the widest point of the circumference of a gemstone. It is the perimeter of the stone that separates the gem's pavilion from its crown. It is also usually the point where a stone is held when it is being examined. Girdles may be described as "thin" or "thick", or they may be more precisely specified as a percentage of the stone's diameter. The ideal girdle is described as being not too thin and not too thick and remaining a consistent width around the entire perimeter of the gem. An excessively thick girdle can make a stone appear much smaller face-up than another stone of the same weight. A stone with too thin a girdle may be more susceptible to chipping than one with a normal or medium proportioned girdle.
Below is a gallery of images showing the ranges and proportions of girdles from thin to excessively thick:
The Gemstone Crown
The crown is the upper portion of a gemstone that begins just above the girdle. The term 'table' is used to describe the flat top of the crown. The crown of a gemstone is typically raised, though some crowns may be cut very high, flat or even concave. In round and oval stones, the crown of a gemstone consists of 'star facets', 'bezel facets' and 'upper-girdle' facets. Star facets are the facets that surround the main table facet, they are typically triangular in shape. Upper-girdle facets, also known as the 'upper-halves', are facets just above the stone's girdle and are also usually triangular. The bezel facets, known as the 'crown mains', are the full four-sided facets between the upper-girdle and star facets. There are a few unique cutting styles seen today that are especially interesting, such as the 'Portuguese-cut'. Portuguese cut gemstones are faceted with an extra row of bezel facets, which result in more sparkle and color; this cutting style is typically seen only with large round or oval stones.
Below are some examples of the different types of crown cutting styles seen today:
|Concave-Cut Crown||Scissor-Cut Crown||Portuguese-Cut Crown|
|Checkerboard-Cut Crown||Buff-Top Domed Crown||Modified Rose-Cut Crown|
- Prima Pubblicazione: May-30-2014
- Ultima modifica: January-22-2019
- © 2005-2021 GemSelect.com Tutti i diritti riservati.
Qualsiasi riproduzione (testi o immagini) è strettamente proibita senza esplicita autorizzazione scritta da parte di GemSelect.com (SETT Company Ltd.).