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  : : Clarity and Cut
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Clarity and Cut

Clarity refers to the internal flaws (inclusions) or the external blemishes of a stone. Flawless colored gemstones are rarer than flawless diamonds. However, even though clarity is important in coloured stones, it does not carry the premium of white diamonds. For example, a valuable emerald will be heavily included, since the natural process of emerald formation is violent, resulting in many natural flaws in even the most valuable of emeralds. In addition, lighter colored stones need to be cleaner, since their flaws can be seen more easily. Darker colored stones can hide their defects because of their depth of color.

The location and the type of inclusion or blemish are important with colored stones. For example, a large crack on the surface of a stone can interrupt the movement of light through the stone, and may also weaken the stone's durability. A large crack would probably detract from the stone's beauty and reduce its value. However, if the crack is small and positioned in a less noticeable area, then it will not affect durability, beauty or price as much as a prominent flaw.

Inclusions may also be used to identify the origin of a stone. For example, Burmese rubies have unique inclusions such as unusual crystal formations that identify the stone as having a Burmese origin. African rubies do not have these unique inclusions, but contain their own unique inclusions, as the geological processes of their formation were different from their Burmese cousins.

More about Inclusions

Most gemstones have tiny natural irregularities called inclusions. Most inclusions are not visible to the naked eye; usually 10X magnification is required to see these inclusions. However, larger inclusions can be seen with the naked eye. These irregularities may be substances such as unfilled cavities, small crystals, fractures or growth patterns within the gem.


Inclusions can be divided into three categories:

Cavities: These may be formed during the gem's primary growth or its later growth. These inclusions can be filled by combinations liquids, gasses or solids.

Growth Phenomena: A few examples of these are solid crystals, natural glass, and limonite tubes (hollow channels stained by iron compounds).

Solids: A few examples of these are solid crystals, natural glass, and white mica inclusions.


Most gemstones have some inclusions, and some stones have more inclusions than others. For example, emeralds are known to be much more included than sapphires. Here is a table that lists the basic inclusion frequency in common gemstones.

 

Generally completely clean Generally eye clean Generally eye included

Beryl
Aquamarine
Golden beryl
Pink beryl

Garnet
most red garnets

Quartz
Citrine
Smoky quartz
Pale amethyst

Topaz
Colorless
Blue

Zoisite
Tanzanite

Chrysoberyl
Alexandrite

Corundum
Ruby
Sapphire

Garnet
Rhodolite
Tsavorite

Quartz
Amethyst

Peridot

Spinel
Red, orange, etc.

Topaz
Imperial

Tourmaline
Chrome, green

Zircon
Blue, green, etc.


Beryl
Emerald
Red beryl

Tourmaline
Red Tourmaline
Paraiba Tourmaline

Cut

Stones either are cut with facets, or are non-faceted, such as the cabochon cut. The cabochon cut is a facetless cut that produces a smooth surface. Usually, this is a rounded dome shape, or sometimes a square dome shape. Cabochons are growing in popularity again, as many people prefer the more subtle, softer look of the cabochon. Some gem lovers claim cabochon cuts have stronger, healthier colors.

Of course, stones are more commonly cut with facets. The angle, number, and placement of the facets is carefully planned to allow the most light to be reflected, so that color and brilliance are best displayed.

The way a stone is cut probably has the greatest impact on the stone's beauty. The most popular cutting methods for colored gemstones may be divided in four categories:

Brilliant Cuts
Step Cuts
Mixed Cuts
Cabochons


Brilliant Cuts

Brilliant Cut Gemstones Brilliant Cut Gemstones

The brilliant cut is popular for many colored gemstones. It ensures that the maximum amount of light is reflected out through the front (table) of the gemstone, displaying brilliance.

In order to heighten light refraction, the brilliant has many facets. The oval preserves the maximum carat weight.

Step Cuts

Step Cut Gemstones Step Cut Gemstones Step Cut Gemstones

Step cuts feature trapezoid or rectangular facets in concentric rows.

Mixed Cuts

Mixed-Cut stones are a mixture of faceted and plain cut.

Mixed Cut Gemstones Mixed Cut Gemstones Mixed Cut Gemstones

Mixed cut gemstones do not usually feature different cutting styles on the same side, but tend to have one plain side and one mixed side.

Cabochons

Dark-colored gemstones, and those that are translucent or opaque, such as opal and jade are cut en cabochon rather than faceted. This cut is also used to display such effects as cat's eye (chatoyancy) and asterism (the star effect). In addition, stones that are heavily included may be cut en cabochon, since it is a better cut for hiding unattractive inclusions.

Cabochon Gemstones Cabochon Gemstones Cabochon Gemstones

Cabochons have a smooth, rounded surface with no facets. The bottom of the stone is usually flat or almost flat.

  • First Published: September-23-2006
  • Last Updated: May-27-2014
  • © 2005-2014 GemSelect.com all rights reserved.
    Reproduction (text or graphics) without the express written consent of GemSelect.com (SETT Company Ltd.) is strictly prohibited.
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