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Post by cpdad on Feb 13, 2007 23:14:24 GMT -5
just wondering ...got to looking at them opal auctions....and doublets...triplets...and mosaic seem to be there a lot...what are they....kev.
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Post by akansan on Feb 13, 2007 23:35:53 GMT -5
Doublets are when the opal has a back added. Really, when two stones are glued together to make a thicker finished stone. Triplets are when a third stone is glued to the top of the opal (generally a clear agate) to add a dome.
You do this when the opal is thinner than "desirable" for a finished piece. It also is used to stabilize the opal sometimes...
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Post by deb193 on Feb 14, 2007 11:04:16 GMT -5
For clear opals, the doublet backing stone is usually dark to make it look more like a black opal. The triplet cap is almost always clear quartz to act as a lens that magnifies the fire. Mosiac means that the center layer is not a single thin piece of opal but a patchwork quilt of small bits of thin fire glued to the backing stone.
Done right, with an excellent layer of fire, this makes a very nice piece. While there is less opal, there is more work and craftsmanship, and with triplets, the opal may be less likely to dry out or crack.
Unfortunately, it is often done shabbily. Small bits of fire that would have no value because of size and thinness are clumsily glued to some dark material - sometimes not even stone - and sold as post ear rings ... etc.
For nice white opal showig multicolor fire and flash, I think the thicker white stone without backing or cap looks best. I have not fussed with opals much since the early 90's but at that time I had not seen any caps put on boulder opal, but I guess it could happen.
More generally, doublets can help improve any transparent stone with fine detail. I am in the process of making some plume agate doublets using black jasper (some of it black pet wood). The dark background makes the lighter plumes really stand out.
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Post by lbowman1 on Feb 14, 2007 11:29:35 GMT -5
You have to watch the doublets and triplets on Ebay. Some of them are bits and pieces of opal--floor sweepings, really--under a plastic dome. Not even real doublets or triplets. I read a discussion of that on another forum. The posters triplets burst when set into a bezel and she discovered the fraud.
Lori
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Post by larrywyland3 on Feb 14, 2007 11:50:27 GMT -5
The clear caps also help to protect softer material that is backed. Man made spinel is used as well as the quartz. The man made spinel is harder than the quartz and is perfectly clear. I prefer the man made spinel to the quartz cap. One thing to keep in mind is that all triplets will eventually break apart. It all depends on the epoxy or "glue" being used. All of these will eventually destabilize. The best will last for 100 years plus. So not really a worry for making something putting it into jewelry and selling it. Just make sure the maker of the triplet or doublet is using high quality epoxy/glue. With ammolite triplets I think it is a shame to make triplets out of them. Some of the high end stones they cap are true wonders of nature and extremely rare, you could spend many hundreds and thousands on these high end stones. Hoping that it will be an heirloom to pass on only for your grand kids to find white spots forming and eventually separation. Once separated the material left is usually to thin to smooth and redo. So it is a total loss. I am pretty sure the same would happen to an opal triplet that was made of high quality opal that just did not have enough material to stand on its own.
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rallyrocks
fully equipped rock polisher
Member since November 2005
Posts: 1,507
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Post by rallyrocks on Feb 14, 2007 12:50:12 GMT -5
With waterline opal like that found in Spencer Idaho and Vernon BC the firey crystal material often forms in such thin layers that it can only be used in triplets. Also the quartz cap works well with the Andamooka matrix opal because even darkened, the matrix is so porous that it pits and can't really be shined up. I posted pictures of all 3 types; solid stone, triplet (backed with obsidian) and the matrix agate with quartz cap doublet, all of which I cut in the last couple of weeks, on this thread: forum.rocktumblinghobby.com/index.cgi?board=ccabs&action=display&thread=1171230882
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Post by freeform on Feb 14, 2007 13:48:16 GMT -5
Ya, i personally think doublets and triplets are made out of demand and nesssity. As most opals ive cut over the years(unless they are matrix opals) are not siuted for jewelry in a solid form beasue A- either a low quailty, or B- the fire occurs in a single plane or varied layer. And having an opal less than 5mm think in my opinion as a solid opal, is not practical for jewelry even if its a high grade piece. IT will break over a short peroid of wear, if not during the actual setting of the opal.
Also, most opals are so small in fire saturation(for the price and demand), mozaics are done to provide a mean to a cabochon, vers just a chip of an earing in size. And as rally points out, there are many opals that the fire only occurs as 2mm in thickness. Again, something you wouldnt be able to cut a solid cabochon out of unless your very lucky. So in essence of retail, i think doublets and triplets came out of demand.
I agree with you Spiritstone, but that can apply to most opals in general. How many 100year opals are on the market? Im sure there are, in private collections. But still something i dout if the case of it still being around, is worn readily by the owner. As specimens i know there is. And from cutting many ammolites, i understand why they are often capped. Becasue theres no way to polish it unless you use stablizers. And to allot of folks, they would rather have a natural quartz cap than a glue cap. If the cutters left the ammolite open, when it needs to be capped. It will only result in low quailty for the jeweler, and ammonite sheel flakes off very easily when not capped. I have cut ones that dont need capping, but over 90% of all ive cut did need it.
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Post by cpdad on Feb 14, 2007 21:11:23 GMT -5
thanks for the teaching everyone...kev
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