Virgin Valley N1 Black Opal Limb Cast - unique color pattern, need help

[SwordfishMining]

Hiya. I've not heard of anybody cutting opal with lasers offhand. Glad the stabilizing is working out so far, slow drying is a much more palatable term as most think the S word means chemicals and the aficionados don't listen as well after that. Glad you found a mentor. A few have crossed my path, but they don't all need the business.
Well I soaked a lot of crazy opal in Starbond before polishing and the coarse hard diamond 80 wheel was the only fast way to get rid of the hard unwanted. Best to preform your material before gluing it into space age polymer harness. You can cut off the great break face for one piece of opal on wood and then on the sawn off face you can tell if any glue penetrated or if any color runs thru the piece further, but you have the one AND if it does not penetrate you have uneven penetration when finished.
So Ive been doing a lot more "as found" "cheap" than high quality blacks for a fine display against a solid wall of competition with brimming cases. I have a few but they wait their next owners. They haven't fallen apart in the decades. The opal is fine as long as it was made fine by mother earth to start with. I will say its HEAT SENSITIVE and don't ever lean on it for polish on a point. The main reason commercial cutting has failed in the past is because they think it can take the heat that some other fields can use burning a glaze on the surface.
The cheaper glued stuff that looks great sells as soon as its done if priced at or below "commoner" opals of the same brightness and POC.
That being said, on natural opal i run it thru a gem saw and the blades have been of varying thicknesses, even to agate blades, for removing potch and splitting nodules. If its already cracked it does not always fall apart.
I've not noticed shattering problems as my wheels were wearing out and vibrating heavily either. Lots of people start on a 220 wheel to baby the rough, not me. The glue grinds right off pure opal and the cutting never "worsened the cracks that i noticed, or made more between the glued together ones. A good saw has little vibration.
You probably have a good color layer running down it as a lot of times it only makes in 3/4 to 1 1/2 in thick bar of play of color from blue to red, big to small that you have to be aware of sometimes. others form from the outside in so the 1" give or take branches are the brightest. The bars in the ribbon patter appear that the color is ninety degrees to it; NOT THAT the ribbon pattern is not where the action is on this one. Picture the bars as split columns of honeycomb pattern or plume. the 360 ones usally have a flagstone pattern on the blue side to a pinfire look on the top side, but every one is different and you just need the surface to be hot on killer N1 stones. Cant wait to see what comes out of it.
It cuts, just not every chunk that comes out. This one has a layer of Marcasite spheres in it. I have a 2,600 ct one in my case, but have not rubbed it down to make it look sexy to be bought. Right now Im chasing a copper deposit before an open pit gets it.

Ozer plus from the Bonanza, just air dried and ground down on a Pixie.

[Shea_O]

cutting opal with the laser it's something new but not sure if is possible
I guess temperature of the surface would be vary hot which isn't good for opals
but you could make some tests with low grade material and maybe it will not explode

btw. grinding is one way of remowing potch and small imperfactions or cracks etc.. but other way is to use thin saw and cut off all the bad parts
> although I don't know how this would work with VV opals ? but I'm sure John can give you all the tips & tricks

Yes I’d need to test some material, the laser method wouldn’t be a continuous beam but quick cuts over hundreds of repeated passes over the same spot. The number of passes/min can be reduced to prevent rapid overheating but there are a few concerns with how well the potch material would hold up regardless and how to keep the stone wet in water while cutting. I have some ideas for that..A thin layer of potch would need to be left behind against the opal itself to buffer heat transfer and then ground down traditionally to the surface of the opal. Its putting pressure on the crack in the brown potch while grinding down to the stone that worries me. The Black Hole has no cracks on it at all, the break on the face is sligtly jagged but was clean from to to bottom. The smaller piece in the videos is what popped off the end. If the sample potch material holds up, I should be sucessful at a low pass/min rate with a laser.

EDIT: I'm going to end up using a slab saw on this

@SwordfishMining
I will be reading your post carefully and have a response this evening or so, thank you

[PinkDiamond]

If you can take pics of the laser cutting it, that would be fantastic to see, Casey.

[SwordfishMining]

I've got more than one opal cut in the case that has a significant bite or something out of the back and the opal on the front keeps it in line. Worst breakage I've ever had in finished stones was aussie whites in the glass cases in the sun, not all of them, but the worst surprises. With virgin Valley opal you kind of expect the cracks to increase over the years as big raw specimens not being finished. I have yet to have a pile of sand from any of it after initial drying. The heartbreak are the dead blacks you think are fine and later do turn out to have centers or outsides that went crazy. More likely you just cant see them when starting as it gets bad usually before you can think of cutting it. Good Luck. time always tells.

[Shea_O]

I’ve added some discussion to the “how to dry opals safely” thread over in the “enthusiast zone”. Worth a look!

viewtopic.php?f=12&t=1407

[Shea_O]

I have an update on this project

I have a black opal parcel I mined from the Virgin Valley, all excavated from the same spot as the black opal pieces I've shown in this thread (in fact some of these pieces in are a part of this ~50ct parcel) that is looking like its less than a month away from being dry! WHOOOOOO!!!!

DRY! 6 months! No crazing!

Can't wait to have this beautiful material cut! Some of this is world class looking. All of this parcel has the complete color spectrum of play in it, some of it in nice sheets.

Included in this almost dry parcel is the piece on page 1 with the rainbow colored peacock tail pattern. If you place a mirror under that piece it has an optical effect of looking like the top-down view of the wedges on the top of a circus tent, spiraling around a central point, in all the colors of the rainbow. It's absolutely astonishing. This face of the opal, set into a ring at an angle with a mirror under it would be an impressive sight to look into. I can't wait to try to see this piece finished.

You can see the reflection effect on the inside of the dome starting to occur at 47 seconds in:

I barely caught it in this video but it looks amazing in person! A king's stone!

I am stoked beyond words to see what potential this material has.

Some day The Black Hole will have to be put to the wheel, I'll risk it. Everything on black. That stone could yield a 30ct cab or more

Of course this is all only possible if the opal lets me do this... its just potential. It will do what it wants... Potential.. Potential....

Some time late in April is when this opal will get cut. I'll be keeping this thread up to date.

Here's an interesting piece that was grey initially in water, like gunsmoke, maybe N4, then turned very dark when dry. Looks like black crystal opal. Maybe a kind of hydrophane effect? There is still plenty of play of color in it, just not showing in the angle of this picture.

[PinkDiamond]

Sweet! That's gorgeous, and that's great that the whole parcel you dug has dried without crazing. That's an excellent testimonial to VV opals, for sure.

[Shea_O]

Here's the peacock flash, completely dry now and no crazing, all is well so far! *Phew!

[PinkDiamond]

That's a relief that it dried alright. Hope it stays that way.

[rocks2dust]

Some nice colors in that!