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Yellowing opal
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Author:  SarahM2718 [ Fri May 21, 2021 7:12 pm ]
Post subject:  Yellowing opal

I bought an opal necklace around 6 years ago. I'm not sure which kind of opal but it was a pearly white colour with the usual array of colours in different lights. I haven't worn it for some time and it's been stored in the box it came in from the shop in that time. I opened it up today and the stone has changed from white to a yellowy colour and whilst some of the different colours are still there, sections of it have become kind of cloudy. I have attached a picture to show you.

Does anyone know why this is happening and if there's anything I can do to reverse it or at least prevent it getting any worse? I'm super upset about it because I love the necklace and (stupidly) only haven't worn it out of fear of damaging it!

Attachments:
IMG_20210521_182637269_MP.jpg
IMG_20210521_182637269_MP.jpg [ 8.34 MiB | Viewed 3563 times ]

Author:  glhays [ Fri May 21, 2021 9:17 pm ]
Post subject:  Re: Yellowing opal

That's sad, some opal have traits of doing this. Not sure of your investment, but taking it to someone to get a positive I'd on the type opal will help in answering if it can be helped any. Do you see any hairline cracks at all?

Author:  1bwana1 [ Fri May 21, 2021 9:29 pm ]
Post subject:  Re: Yellowing opal

Try this. Place the opal in a jar that can be sealed. Also place in this jar a small shot glass of water. Do not put the opal in the water. Watch the opal for a few weeks and notice if starts to revert to its old color, transparency and fire.

There are two basic types of gem opal. The first can loose its water and that is it. It cannot regain the water. It is often stored in the manner I describe above because although it can't restore it can slow down the loss of water in the opal. Normally there is some crazing in this type of opal when it loses its water. This is typical of Australian Opal.

The second kind is called Hydrophane Opal. It is thirsty for water. It will soak up the moisture in the jar and revitalize itself. In fact if you put this type of Opal in the water it will absorb so much that it sometimes goes clear, and looses its fire. As it dries out the body color and the fire returns. This opal mostly doesn't craze in the beginning stages of drying out. This is typical of Ethiopian Opal.

There are also Opal polymer treatments that are sometimes applied to the hydrophane opals that will absorb it the same as it does water. Over time the polymers tend to turn yellow. If this is the case with your Opal I know of no way to get rid of tyhe yellow color.

Good luck, and keep us informed of how the experiment is going.

Author:  dchallener [ Mon May 24, 2021 1:02 pm ]
Post subject:  Re: Yellowing opal

I have an extremely nice ethiopian opal that did the exact same thing. I have a friend who said he had a technique for changing them back, which he tried, but nothing happened to the color at all. It is still yellow. Very nice yellow, with wonderful fire. But when the cutter was cutting it, he told me that he kept losing it when he put it in water, because it was so clear. That clearly would not happen now.

Author:  Barbra Voltaire, FGG [ Mon May 24, 2021 2:52 pm ]
Post subject:  Re: Yellowing opal

I have a strand of faceted Ethiopian opal beads. Same story. White when I bought them, golden now.
They still have a lovely play of color, but I find the yellowish background color harder for me to wear. They were stored in a jewelry pouch in the safe for about a year. Brought them out last week.
"Oh, dear" said I, out loud. :shock:

Author:  JackTrick [ Mon May 24, 2021 5:28 pm ]
Post subject:  Re: Yellowing opal

This thread has me gazing with suspicion at all my Ethiopian opals.

I’m trying to be very careful with their exposure to any forms of liquid...

Author:  dchallener [ Mon May 24, 2021 5:54 pm ]
Post subject:  Re: Yellowing opal

It clearly wasn't liquid. Mine was stored for about 3 years in a jewelry box, and the color change happened.

Author:  1bwana1 [ Mon May 24, 2021 7:48 pm ]
Post subject:  Re: Yellowing opal

dchallener wrote:
I have an extremely nice ethiopian opal that did the exact same thing. I have a friend who said he had a technique for changing them back, which he tried, but nothing happened to the color at all. It is still yellow. Very nice yellow, with wonderful fire. But when the cutter was cutting it, he told me that he kept losing it when he put it in water, because it was so clear. That clearly would not happen now.


Stephen, try putting it in water. I bet it goes clear again as it absorbs water. Try resting it on your tongue and see if it sticks a little as it tries to absorb water.

Author:  Barbra Voltaire, FGG [ Tue May 25, 2021 4:39 pm ]
Post subject:  Re: Yellowing opal

No liquid contact with mine either......no sticking on the tongue.....do you think that our opals may have been stabilized with something which is discoloring?

Author:  1bwana1 [ Tue May 25, 2021 5:36 pm ]
Post subject:  Re: Yellowing opal

Barbara, I have read reports of that happening. But, have never experienced it myself. Once the opal has been soaked in polymers it will no longer absorb water or stick to your tongue.

As I have aid, if you put in water and see what changes in body color, and temporarily. Once you take out it will begin loosing color and revert back. There is little to no risk in doing this.

Author:  dchallener [ Tue May 25, 2021 7:31 pm ]
Post subject:  Re: Yellowing opal

I bought the rough and sent it to a cutter in the US, who had never cut opal before. I am certain he did not treat it.

Author:  Barbra Voltaire, FGG [ Tue May 25, 2021 10:22 pm ]
Post subject:  Re: Yellowing opal

I timidly ran cold water over the beads.
Then I thought, what the hell, I'll add a little clear dish soap.
That certainly cleaned them up.
2 photos now:
Body color on white paper and play of color on a fig tree leaf.
Image
Image


'll go soak them in some H2O and see what happens. :smt017
Updates tomorrow.

Author:  Barbra Voltaire, FGG [ Wed May 26, 2021 12:36 pm ]
Post subject:  Re: Yellowing opal

After soaking overnight in a water bath, they have gone quite transparent, still holding their play of color.

Attachments:
op.jpg
op.jpg [ 239.05 KiB | Viewed 3361 times ]

Author:  1bwana1 [ Wed May 26, 2021 12:57 pm ]
Post subject:  Re: Yellowing opal

As predicted.

That indicates to me that they have not been stabilized with some sort of polymer. That is a good thing.

They will become more translucent over the next few weeks as the water comes out. It is good that they maintain their play of color.

It is hard to tell on the wood background whether the body color is still yellow tinted. Can you post a picture on a white background?

It may be of interest to post update pictures as the go from transparent back to translucent.

The joys of hydrophane opal....

Author:  glhays [ Wed May 26, 2021 1:34 pm ]
Post subject:  Re: Yellowing opal

Some years back I purchased some cheap Ethiopian opal from a vender at the AOS show as all the opal I had worked was of other variety's. Well the story goes do not use a Sharpie to mark out guides on hydrophane opal, although the bluing effect did look a little attractive.
I have also removed yellowing and iron staining from Australian opal (Coober Pedy) with a mixture of 60/40 Muriatic Acid/Water solution done before polish. Not sure of the lasting effect it may cause over time, considered something more than likely destructive in nature but it did work. Not something I am suggesting here, or on any opal for that matter and strung opal beads.

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