Crystal and “white” opals usually look better on a black background. Some jewelry with these opals has a black backing to better show the colors. I don’t mean making an opal doublet but applying a something to the stone’s rear surface.
What materials are commonly used for this and how are they applied?
Is this considered treatment?
Hi Joseph! Welcome to the community!
If you haven’t seen this article on Opal , it is a good reference.
Placing a surface coating on any gemstone including opal is considered an enhancement, however, there are some who would consider it a treatment.
I don’t have a list of specific materials that could be used, and honestly, IMO, they detract from the gemstone’s natural beauty.
I have repaired opal pendants, brooches, tie-tacks and a particularly memorable bolo tie, where some of the stones were assembled doublets and others had been “painted” with a dark paint or dye.
I have also worked on several pendants where the bezel surface had a dark patina which contrasted the base metal (sterling silver). The opals were untouched, which was really awesome to see! It also made it much easier to work on.
Hopefully this helps!
-Troy
Yes, thank you. I am definately not referring to doublets.
With some crystal opals it makes a big difference if the stone is shown on a white background or a black background.
I wonder if a bit of black cloth backing would enhance the appearance of a crustal opal pendant in an acceptable manner. I would not wish to permanently treat the stone or mislead a buyer.
A pad material could definitely be used, but most opals require hydration. Which means the stone and most-likely the pendant would need to be submerged in mineral oil or water occasionally. A cloth would end up becoming saturated and moldy after a while. A hypoallergenic material such as plastic would be a better option.
It would be a good practice to inform your customer about the backing material in the setting and the proper care of the opal.
Hi Joseph and All,
There isn’t anything wrong with assembled stones as long as they are not sold as solid opals. I think that the correct nomenclature is assembled rather than treated. Doublets can be opal with a cap on top or opal with a black backing. Triplets can be an opal fire layer with a glued-on black backing and a glass or clear quartz cap. I have a few really nice doublets somewhere which are very thin layers of white opal with pinfire, greens, blues, reds and oranges with some kind of black backing. They were very cheap compared to what you would pay for the equivalent solid. IDK what the backing is, because it looks like brown wood grain on the back! These latter stones are a good way for someone to have a very nice piece of jewelry that looks great without spending a lot of money. Disclosure is the key. Just don’t try to sell a piece with a $35 opal set in silver for $400, which is probably a low bound on what a similar appearing solid opal would go for. Also, I suppose at some point the epoxy might fail, but then I also suppose that most people eventually are going to do something to a solid opal, right? They are somewhat fragile and may not last forever without very careful care.
Black backing could be onyx or black glass or black jade or something else. These doublets can show glue bubbles in the cement layer if the glue was epoxy that was not mixed well. Ditto for opal doublets that have a protective quartz cap. The cap protects and also magnifies, esp. if it is a high dome. The effect may be too fakey if the dome is very high, I guess. I suppose you know that white opal can be burnt with sugar to mimic the very pricey blacks, right? I think the operative lapidary command would be: “have fun and make lots of jewelry…but always disclose correctly.” -royjohn
Thank you all for comments. I am still trying to figure out simple, acceptable, non-permanent solution. Important not to misrepresent stone or treatment.
Joseph I don’t know but I believe you’re asking about an oxidizer for jewelry if that’s not what you’re asking about that’s probably what you should be asking about when you touch a stone in any way it’s going to be considered and enhancement maybe even a treatment anything you do that is changing it in any way other than a cut and polish people are going to want to lower the price on it and call it at a minimum a color enhancement it’s nothing wrong with putting Stones together doublets as long as you’re honest and up front about it but what I believe you might be asking about and this is a commonly used technique especially with opals when making the jewelry so when I do a swing or a bezel I use an oxidizer on the grocery silver that turns it pretty much black you can use different oxidizers to get different colors with opal you normally want a black setting if that’s what makes the stone look better you can test by putting it setting the stone on something black or something the same color as whatever you’re looking for then you find the oxidizer to achieve that color it basically oxidizes the metal on the finish of the setting so inside the bezel where no one’s going to see it because it’s going to be behind the stone that will give the stone the effect of having something black behind it without touching or altering the stone at all I’m not sure if that’s what you were asking about but it’s the best way that I know and use often
In the past i have used both high quality black finger nail polish or black epoxy in the bottom of a solid backed bezel setting for some Welo opals. The stone is not touched, just set over a black background. I always inform the client and let them choose whether or not to blacken the background. They always choose to have it done. It’s just like viewing opals on a black velvet display pad. The whole purpose of jewelry is to adorn the wearer, and that helps a lot for lighter and more transparent opals.
That’s an excellent approach and so much easier to apply than cut a precise shaped plastic, as I have done… don’t know why I hadn’t thought of that! Thank you! 
Thank you for the ideas. I really don’t want to treat the stone and this seems like a good way to enhance the appearance without treatment. Thanks everyone for your help.
I searched the internet high and low trying to find out more information about backing a piece of opal but could not find out very much. Having worked with a lot of turquoise in the past years backing Turquoise is an accepted practice to keep the stone from cracking during cabbing.
I had some pieces of Ethiopian Opal and decided to take a risk of backing them before cabbing. Opals are different but Ethiopian Opal you don’t want oils on them nor do they need water for enhancement to get more color out of them so those I do use a black cloth behind them when building them into silver jewelry. I have read where folks will paint or use black magic markers to darken the back of the stone to bring out the colors better, which it does a great job. The issue is paint or marker will wear out over time and then the stone looses that black backing. So I backed 5 pieces of opal with DevCon, commonly used for backing Turquoise, then cabbed them. The DevCon will last almost forever. The worry was that Opal absorbs so much water during cabbing it actually expands in size and weight where the DevCon won’t, making the opal crack?? I tried this experiment and cabbed the stones just two weeks ago.
Out of 5 stone one cracked, I will cut that and re-cab it. The other 4 turned out amazing. As long as they are sold with full disclosure about the backing, I see now problem with doing that.
Thank you for this very useful information.
Does anyone know if IGS has an article or the forum has a post about applying water, or oil, to Australian and Ethiopian opals? Is oil considered treatment? How and how often should water be applied?
Here are three articles on IGS:
The use of mineral oil as a hydration technique has been used for years… but I always caution my customers that using oil could be considered a treatment and that filtered or distilled water should be used instead. I also advise against the use of de-ionized water for any cleaning or hydration, as it will leach out essential minerals and will damage metals such as copper and nickel.
Cheers!
Thank you!
Should I just would like everyone to know because I feel like I started this direction that I did not want to mislead anybody accidentally so I have searched high and low in the requirements for disclosure of enhancements and treatments it seems to be hit or miss so just so that we are all doing what is appropriate because in this business all you have is your reputation and once you mess that up it’s over as far as I’m concerned I honest to God believe that if I was the one that made you lose your reputation I would expect there to be consequences so keep that off of my conscious I think the best thing at this time is to ask the IGS to step in and tell us what day know since they are one of two of the most reputable trustworthy authorities in the industry the other one would be gia in my opinion they can probably set this set this straight so that we don’t chance our licenses I would never tell somebody to do something I haven’t done so yes I have absolutely like I said in my last comment backed the inside of bezels rings I don’t see a problem with it but researching after I wrote that I did find a source that said that it should be disclosed I personally disclose everything because I’m passionate about my pieces and all the work and time that I put into them when someone is actually interested enough to sit there and listen to all that and get excited and I know that they’re probably the person for that piece and when you’re asking someone to spend thousands or tens of thousands of dollars on a piece of art that is yours that’s when you know you found the person that is rightfully should go to but there’s so many different places that we are all in in our careers or hobbies or passions whatever wherever you are that I think clarification should be given
Thank you for your clarification. I am not certain it was needed as I don’t think your comments were misleading or inappropriate. If I understand you correctly, you suggest modifying the setting metal color, not the treating the gemstone. I don’t see any difference from rhodium plating.
You raise an interesting point; it would be helpful if the IGS, or other organization, would issue guidance on Opal treatment. Treatment technology and its acceptance seems somewhat in flux. Treatment of some gemstones is almost expected.
I agree with @JosephT32847! Your clarification is appreciated but I don’t think you have or are misleading anyone with those comments. If anything, your voice on approaching methods of handling opal and interactions with customers is very much welcome!
That is the beauty of this forum and the support of IGS and its members! We are all here to learn and exchange our experience / thoughts…
Hello John,
You are correct that any treatment or enhancement of the gemstone itself should be disclosed, and it’s important to explain to your customers exactly what was done to the stone. This includes creating an opal doublet or attaching any kind of backing to the gem itself, like foil on a rhinestone. (This doesn’t include cutting and polishing, which is not considered a treatment or enhancement). However, the practice you and denghausen have described only involves the gem setting. Oxidizing or coloring the back of a setting doesn’t alter the gemstone in any way. In fact, doing that for an opal is really not much different than using a yellow gold setting for a white diamond with a lower color grade. I don’t think you should feel morally obligated to disclose the “black setting” as a gem enhancement. But I think you should consider telling your customers about how the “black setting” works. It would make your jewelry setting a selling point, something that will stand out in contrast to other jewelry pieces. It’s a way of bringing out the natural beauty of the opal without altering the stone itself. Some opals look really good against a black background, and you have a way for the customer to carry that effect built-in to the ring.
So there we have it I knew it was not a gem enhancement or alteration but I never want to mislead you guys and there’s nothing wrong with being thorough I did research you myself for at least 2 hours so now that I’ve turned this into a whole ordeal I went back to the source of the conflicting research and the exact wording was you should communicate processes like we’ve discussed but that’s their opinion everybody should do whatever they feel is correct the law and your reputation don’t give a damn about should as long as you can sleep at night then you should do whatever you think is best me personally I always put the piece of jewelry and stone first I don’t give a crap who buys it when I’m making it I don’t think about any of that I just want it to be the best when I Make a piece of art like a Ring i want that ring to be the best ring ever if I do a carving I want Patrick dryer to envy it I guess if it’s Patrick I would accept appreciate but if it’s a carving anyone else other than him needs to envy it and when I’m done cutting a gemstone then making a piece to best display that gem when I finally become done with it I’m so proud of it that I can’t help myself when someone’s interested in it or questioning something about it i go on a crazy tantrum of pointing out small details and techniques that I might have used of course I try to keep it under 5-10 mins no one wants to hear someone become manic when describing how nice something they did is especially if they don’t question or give a crap about what you’re so proud of so I’m not suggesting anyone else do this unless they have a good presence of mind in the ability to read body language as well as a small understanding of psychology to know when someone is ready to stop hearing what they are starting to consider manic mumbling. The most important thing I really wanted other members to see in this form is how easy it is to get one of the most respected authorities on every subject these forms could be talking about from gems & jewelry to mineral specimens IGS has people that are smarter than me smarter than you when they combined their knowledge even if you are the Albert Einstein of jewelry you can use them as a tool no matter what level membership you have you can ask them to clarify just like I did and look how fast they came in straightened out my concerns with their knowledge of opal jewelry they gave a straight factaul answer and when it comes to Opal I personally am in oprlaholic I’ve been addicted for coming up on 4 years now people have tried to get me quick but I can’t stop using it just grabs a hold of you ,your wallet your life ,friends can all disappear because you fien those flashes of bright red that turns Orange then blue then gold and green all in the same exact spot as you rotate the stone sorry to cut this one short guys I think that was a trigger I’m going to go cut some opal
Thanks for the link, Troy. That is by far the best single source of concise opal info I have seen, very helpful!