Don
Cave Dweller 
He wants you too, Malachi.
Member since December 2009
Posts: 2,616
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Post by Don on Sept 11, 2012 12:10:25 GMT -5
I'd like to hear some pointers from the opal cutters on how they evaluate a piece of rough opal and gauge it's cutting potential. The reason I ask is that I have a client who wants to trade rough for jewelry, but I don't have a good eye for the rough beyond the basics, i.e. fractures, shape, size, look for layers of color, etc. The opal rough I've been shown is white material with a few very thin layers of color showing. I'll add a pic of the piece I've been given as a sample this evening.
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Post by FrogAndBearCreations on Sept 11, 2012 12:21:43 GMT -5
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hand2mouthmining
spending too much on rocks
Purveyors of California Gem Rock
Member since September 2011
Posts: 495
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Post by hand2mouthmining on Sept 11, 2012 15:15:24 GMT -5
Hi Don! I hesitate to trade finished jewelry for rough, since values are so subjective. Opal poses even greater challenges in this respect. To begin evaluating the opal, look at it both wet and dry. If it's been stored wet in a jar, examine it from all angles wet, noting thickness of color layers. As it dries, cracks and flaws will be revealed. That's why opal is stored wet, to show off the fire and hide cracks, especially in Mexican opal. Wet storage will also keep rough opal hydrated, concealing any stability problems. Now, turn the stone 90 degrees. This is the oreintation from which you'll be cutting down to the fire layer, since customers prefer a wide play of fire. Be aware that, in my experience, a thin fire layer will show far less fire when turned to show the face of the layer. Remember, even if the layer is thin and fire seems week, an attractive pattern or wide flash can be turned into a killer doublet or triplet by using a dark backing stone. Consider the width of the face of the fire layer, and what you'd make out of it. The thickness of the no fire opal material (aka "potch") will dictate whether you can use it as-is, or if you'll need to slice for doublets or triplets. If possible, ask your client for location info, and if from Australia, "field" identity. This will help you to web search (www.ixquick.com for anonymous search) for stability info. Stability varies from field to field, and even within a field. Take your time and get knowledgible. Take a few minutes and browse the current opal offerings on eBay, noting prices and locations available. Use the Market Research tools, too. This has a dual purpose; It shows current "real" market values, and allows you to better control your instinctive desire for the stone. (I fall in love with stones all the time!  Most importantly, be accurate and detailed in assessing the true value of your fabricated work. Of all the factors involved, the one least valued and most easily discounted is your time. Assess thoroughly the materials cost at todays replacement cost, not what you paid last year. After all, you're going to need to turn the opals into jewelry, too. Personally, I'd ask cash for materials cost, and accept (crucial word, that) rough only for your artisanal efforts, especially for opal. Cutting opal is an art, not a science. Treat it as such, and you may find it addictive.  A happy addiction, for sure! Good fortune, sir! Kris |
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Don
Cave Dweller
He wants you too, Malachi.
Member since December 2009
Posts: 2,616
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Post by Don on Sept 11, 2012 22:02:42 GMT -5
Thanks Kris, that's the kind of info I was looking for. I appreciate it!
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