opal play of color to produce a cat's eye effect

facetwiz · **Joined:** Thu Sep 16, 2010 10:11 am **Posts:** 2

Has any one done any research in what causes the play of color to produce a true cat's eye effect(chatoyance line ) in precious opal with no evidence of any fibers being present under high magnification.

Barbra Voltaire, FGG · **Posted:** Fri Feb 14, 2014 11:16 am

Can you post a picture?

facetwiz · **Joined:** Thu Sep 16, 2010 10:11 am **Posts:** 2

Here is sample image of one of two opals that were examined.
sample seen here there are no fibers associated with the catoyance that can be seen -neither the start nor the end of a single fiber could be identified. The fire in the eye penetrated down into the body of the opal similar to seeing rain falling at a slight angle

Elena Andia · **Posted:** Sun Feb 22, 2015 7:53 pm

I think it is very rare that a stone could display cat's eye effect without the presence of fibrous or needle-like inclusions.

dchallener · **Joined:** Mon May 26, 2014 9:42 pm **Posts:** 926

I have seen some like this from Idaho. Also a "star" which consists of 6 points of light, alternating in color red blue and green. Don't know what causes it though.

Qld Barry · **Joined:** Sat Jul 14, 2012 5:11 pm **Posts:** 657

This effect is found in Australian opal.
I have seen Lightning ridge "jelly", with "aurora" like veils, drifting thru the gem.
Also have seen "cats eye effect".
Ross Sedawie, a forum member, is an opal expert, he may have some photos to share?
You must remember how some opals are formed, liquids permeating the sandstone, for example, and so layers of colour are easy for nature to lay down.
Barry.

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