How to tackle the impossible faceting

[agemcutr]

I got a problem,Im trying to cut what should be easy but it aint.Its a piece of West Australian Orange jelly opal. Ive cut Lightening ridge material with ease but this is volcanic,and has isuues with grinding the rough during the prep.You have to grind it to completion and leave no minor glistes or cracks whatsoever and you cant get back to it later,unless you need two or three stones from a single piece of rough because thats what you will get.Dont leave it in water and dry it after grinding to keep as much moisture out as possible till it is clean. Leave it overnite so that any missed crazing shows up the next day and it will.Once its dead clean its like any rough but dont overheat during dopping prewarm the stone well.
Now the cutting process. Well it just like any opal.But you need to dully cut all the facets. No fast cut and polish system for this stuff.
Now prepolish it with a copper 14,000(tryed 8000 too course)lap,you can just wipe your 3000 lap clean and soon the 14,000 will take over.
Now the fun begins.
I first tryed type metal with 100,000 but got cathair lines,so i  tryed tin,corian,lastlap,darkside, batt, my new alloy(best so far but not by much and no where near enough.) OK so im out of laps so i went into the workshop and fished out some old laps and came across an old lead lap i made for rare stone cutting.What the hell I may as well try.Finally it owrked. So lead with 200,000. But it wasnt just that easy it never is.
The cathair lines were still there but very faint.So now it came down to technique.
I tryed fast slow powder with baby oil,wax compound.all worked butthe lap was stripping itself being so soft. So it must be conditioning. That was the key the lap nneds to be well conditioned before it works. plenty of powder and a little oil and lighy faceting on dummy facets till the lap blackens, the 1500 RPm and no sharp edges gave the result. BUt it wont win a comp.
So that been my day. i think Ill stick to diamond. Blacklung V lead poisoning.

Regards Anthony

[mehoose]

Anthony, try cerium on either the darkside or just an old cheap perspex.

[Bucket]

Jeez Anthony, here I am with a nice piece of honey coloured opal (with colour) to facet and you're having trouble, you've really put the wind up me now!

[agemcutr]

Actually i used to polish this with Linde B on a tin/lead lap many years ago. But that was
sedimentry opal not volcanic. Its easier to polish in small pieces. The larger any stone it becomes difficult because I believe the polish squeeges out from under the facet and heats up the face very quickly at low and high speeds.But its irronic that the best lap is lead. At high speed it performs like a batt lap and is the cheapest metal. But keeping it in condition isnt easy as you are constantly stripping off the layer of diamond.I have 12 facets to go on the pavillion . What a marathon it is.Ill post a photo of the pavillion.

[Bucket]

Phew, the piece I've got is sedimentary, sounds like that should be easier, love to see the photo when you finish it.

[agemcutr]

Pavillion is done,I tryed the darkside with 100,000 cerium and holy cow. Also the same with corian .with a relatively good result with 100,000 about the same result as the batt lap.

[agemcutr]

Ive just transfered the stone using a low heat wax(grey from a jewellers supply,rigid not flexable)I first preheated the stone on top of my halogen lamp.Photo supplied.

Regards Anthony

[mehoose]

does that mean I ain't just a pretty face?

[Fissan]

Some good ideas in here, I have just been given some fire opal from WA to see how it would come up and my first test run I found I was having the edges "pop" and chip but I was trying to grind it like a piece of CZ