Just recently, I cut this big chunk of sapphire in 2, reveiling a really nice Trapiche star. So, with that sucess in hand, I guess I'm going to have to buy some new cabbing laps, and in the near future, do some star cutting! The surface has honey on it, to bring out the rutile rays.
I love trapiche sapphires, though I prefer them as polished slices rather than cabs. I have the darndest time getting the ones I have to take a good final polish, though (lots of c-axis perpendicular fractures, I suppose.) Just goes to show the kind of rough I can usually afford I can't wait to see what you produce from these!
I gave away a packet of opaque blue sapphire similar to these but much smaller, probably 8-10mm in diameter. All had the same rutile trapiche in the middle. I personally don't like them and as they were sold to me as "star sapphire" I was not happy.
I had no idea that some people consider them valuable! I gave them away in disgust to someone who wanted to try cabbing sapphire...
I will have to look to see if I have any stray pieces lying around to cab and see if I like them any better now
-Allan
_________________ Allan Aoyama http://www.omnifaceter.net <- Omnifaceter is back online!
Allan, good star sapphires are just so rare, but Trapiche, we find often, and in the past, I have never bothered to do much with them. Now, however, with rough becoming so expensive, I've looked again at all my inventory. A well polished Trapiche is actually quite a gem, albeit not with the same "zap" as a "true star". I will buy some new star polishing laps, and ultimately, report on the results. Sometimes, a really unusual one comes out of the dig, like this one. It will cab to a golden sheen, all over the intense black/blue base, and will be something very special, I think.
@allan: Back in the day these were called 'fixed' or 'stationary' stars. I suspect the branding of trapiche emerald helped elevate their status, but they are very charming when polished. That said, there are multiple varieties: true trapiches like those found in Burma which are showing the exact same phenomenon as classic trapiche emerald, a type which just has 6 dark lines (perhaps the same as the first type or the third in origin, much less exciting in appearance), and these like Barry has, where the lines are defined by extra concentrations of silk. This last type is my favorite and they can be very lively/lovely when polished thanks to the reflective silk. EDIT: for the record I was a bit wrong here. The broad phenomenon is the same across all these sapphire trapiches--it's just concentration of including minerals to certain zones of the crystal structure. The question is which inclusions--in those trapiche rubies it's calcite or dolomite, in those sapphires it's often rutile.
@Barry: that looks cool! I wonder how it would look faceted? Iirc someone posted some pictures a while back of black-base bronze Thai star sappires which had been faceted c-axis up and the result was pretty neat.
Scaro, I've seen some faceted, like you describe, and they are awesome. I have some smaller ones that might work like that. I will "dig" them out, and see if one might suit you. Sometimes, just sometimes, these big lumps of corundum, actually have a "heart of gold", a pure, gemmy centre, only found by slicing them open. From my "History of Gemfields" manual; Jul 4th, 1946. An old miner, known as "Dick the fiddler", found a 225ct golden yellow at "Big Bessie" diggings, but thinking it a "bomb", a descriptive word for poor quality sapphire, sold it for $2. It was sold again, the same day, and subsequently taken to London, and once cut open, a 75ct gem was obtained, which sold for $600. The Big Bessie workings are still delivering big stones to any-one finding a virgin patch of ground. It was all 6inches, to 1 foot deep, but badly damaged in the 1980's by illegal, night-time activity, using bulldozer to rip it up, and all the wash was carted away. The whole of this area is now a designated "fossicking zone", so well protected for visitors who are prepared to do some serious pick/shovel work.
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