CIBJO releases Gemmological Special Report: considers process of separating measurable facts from opinion; See Gemological Articles below.
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 Post subject: Agate discoloration
PostPosted: Sat Apr 22, 2017 2:05 pm 
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Someone gave me an agate rough and a polished one. As the color is vivid and suspicious to be treated (dyed maybe), I tried to immerse them in tap water. Colors from the rough was soluble into the water, but not for the polished one. Acetone test also cannot take the color off.

Since my friend told that he found it naturally in a mountain area, is it possible for agate to be colored with soluble agents ?

Then why the colors are stable in the polished stone?

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 Post subject: Re: Agate discoloration
PostPosted: Sat Apr 22, 2017 2:09 pm 
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Nah, that is definitely dyed. The colors and distribution are both very unnatural. The cut stone has already been exposed to a lot of water during cutting, so it is my guess that the easily-removed dye has already washed off, leaving the more deeply soaked in dye that would taje longer to soak out

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 Post subject: Re: Agate discoloration
PostPosted: Sun Apr 23, 2017 10:34 pm 
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Location: Wylie Texas but in Alaska for a while
iwakasu wrote:
Someone gave me an agate rough and a polished one. As the color is vivid and suspicious to be treated (dyed maybe), I tried to immerse them in tap water. Colors from the rough was soluble into the water, but not for the polished one. Acetone test also cannot take the color off.

Since my friend told that he found it naturally in a mountain area, is it possible for agate to be colored with soluble agents ?

Then why the colors are stable in the polished stone?

Image

Image





I hate to sound negative, but I have a few "friends" that I do not trust. I hope that he "comes clean" with you.


But to your original question, and this is just a guess.

One of the polishing theories is that there is a plastic flow involved. (a modification of the Beilby theory). There may be enough flowing of some sort to help seal the surface.

Just a guess


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 Post subject: Re: Agate discoloration
PostPosted: Mon Apr 24, 2017 1:19 pm 
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Definitely not natural but that would be a difficult dying process.


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