What is Chatoyance? or Cat’s-Eye Effect in Gemstone and Minerals

Today we will discuss gemstones and mineral information regarding chatoyance effect. Let us first see what is actually chatoyance?

What is Chatoyance in Gemstones?

[caption id="attachment_2531" align="alignright" width="154"]Chatoyance in Gemstones Chatoyance in Gemstones[/caption]

Chatoyance is derived from the French word "chatoyer" which means cat and "oeil" means eye. Chatoyance is a bright streak or a bright band of light across the surface of a cabochon. It is abundant parallel inclusions which cause cat's eye. It should be long, thin, needle-like. It must come and form in a cabochon. Reflection should take the form of light at a right angle to the inclusion.

Tiger eye

Chatoyancy is an optical phenomenon. A band of reflected light moves under the surface of a cab or cut gemstones and mineral. Tiger's eye and Chrysoberyl are two best example which usually has this type of phenomenon. The cabochons are used in jewelry. Cat's eye effect occurs in gemstones and minerals containing very thin parallel inclusions within the gems. This is called " silk". The light actually reflects from these parallel inclusions and form a band across the stone surface. It should occur always at right angles to the length of parallel inclusions.  Read here about the type of inclusions which are found in gemstones and minerals.

Following attributes of a cat's eye stone should e:-

  1. Needle-like inclusions
  2. inclusions should be abundant
  3. must be cabochon
  4. Right angle
  5. fine needles

Type of inclusions in Cat's Eye Gemstones and Minerals

The inclusions in chatoyance affected stones can be of various kinds such as crystals, linear structure, hollow tubes, needles, hematite. They appear throughout the stone and aligned at the crystallographic axis.

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