Stones I have cut

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I usually polish with cerium at low speeds, not the least because it's mixed with water and doesn't stick to the lap like diamond in a greasy base so can get very quickly flung off at high speeds.

It the perspex lap scored? It shouldn't squeak much if it's both well-scored and wet enough.

What lap did you use to cut the facets in with?

Quartz can be twinned. A geologist tells me that technically, most quartz is not twinned but he agrees that perhaps a disproportionate percentage of facetable quartz crystal material may be. I've noticed this sometimes, with the polished surface having what looks like overlapping plates, not usually visible to the naked eye but can be annoying.
 
Lefty said:
I usually polish with cerium at low speeds, not the least because it's mixed with water and doesn't stick to the lap like diamond in a greasy base so can get very quickly flung off at high speeds.

It the perspex lap scored? It shouldn't squeak much if it's both well-scored and wet enough.

What lap did you use to cut the facets in with?

Quartz can be twinned. A geologist tells me that technically, most quartz is not twinned but he agrees that perhaps a disproportionate percentage of facetable quartz crystal material may be. I've noticed this sometimes, with the polished surface having what looks like overlapping plates, not usually visible to the naked eye but can be annoying.
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Agree with the speed issue, but not much I can do without changing motor, belts etc, stuck with the speeds I have, the low speed (750rpm) works well with diamond polishing but have to be careful about pressure on the stone as it can go too far fast.

Lap has been scored and is fairly well aged, the cerium seems to grab it well.

Final cut on the stone was with 3000.

Not sure about twinning as I am unsure what to look for. Piece I am working on is crystal clear, no inclusions, nothing to mar the clarity.
 
You won't readily see twinning in the rough stone itself - it's microscopic layers with the crystal grain reversed with each one (if my understanding is correct). First layer has the crystal grain running one direction, next layer on top in the opposite direction, third one back in the original direction and so on. There's probably technical inconsitencies with that description but I have often seen the effects.

I still use plated #3000 laps from time to time - cheap and wear out quick but all the ones I've used have cut nice and flat and accurate nonetheless.

When sweeping the lap, I try to avoid the portion nearest the centre as the facet is getting close to finishing cutting. It seems to "rip" at the surface in a more aggressive manner than the outer portions - perhaps because the diamond particles are turning in a tighter arc relative to the the stone? Not sure but there's a real effect there.
 
Well here i am cutting two man-made gems in a row. After seeing the CZ Whirlpool, Dad reminded me that I still had a piece of "Tourmalike" that he bought from a gem show a few years back and that I never got around to cutting for him.

Researched it up as best I could to try and ascertain the properties of the material. It appears to be a form of fused quartz. This piece displays a full colour change effect depending on the kind of light. Here it is in Akhavan's "Eye of Zul". First in incandescent light (natural daylight produces the same effect)...........

1527683540_20180530_221606.jpg


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And in fluorescent light........

1527684688_20180530_213453.jpg


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Gotta stop cropping the best photos, seems to stop them from uploading. Anyway, gem weighs 11 carats and measures approx 15mm from base to apex. Out in the hallway where the incandescent light from tbe bedroom was mixed with the fluro from the bathroom, the gem was pink and green striped but the photo wouldnt come out in the low light.
 
Interesting, never heard of the material before but looks a lovely stone. Colour change is fascinating, one of the Nanosital pieces I have does a similar change, code is ANZ-1536, goes from a golden colour to green under fluoro, even daylight fluoro. Going to make it fun when cutting, overhead light is daylight led so golden colour, side light for inspecting is daylight fluoro so will switch colour when checking facets! Definetly only one glass of wine over dinner if I'm cutting at night 8)
 
Dihusky said:
Interesting, never heard of the material before but looks a lovely stone. Colour change is fascinating, one of the Nanosital pieces I have does a similar change, code is ANZ-1536, goes from a golden colour to green under fluoro, even daylight fluoro. Going to make it fun when cutting, overhead light is daylight led so golden colour, side light for inspecting is daylight fluoro so will switch colour when checking facets! Definetly only one glass of wine over dinner if I'm cutting at night 8)
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Cheers mate. Yeah, it just came in the little packet with the name and nothing else so I had to go searching so I could at least work out things like critical angles, best polishing agent etc.

The tiny bit of info I could find on it suggested it was some kind of fused quartz and that the RI could be anywhere between that of feldspar and that of topaz - not a lot to go on. I raised the culet angle a little so that it wouldn't outright window if it were as low as feldspar. Going on the look of the finished gem, I'd say the RI is higher than feldspar. It's pinkish in incandescent/natural daylight, green in fluro and under LED it kind of loses most of it's colour, looking like very, very pale smoky quartz (but still very sparkly).

It polished very nicely, very quickly and very easily with cerium.
 
StoneTheCrows said:
Hi Lefty love ur work
How many hours would you put into that one stone
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Cheers mate :Y:

Hmm, that's a good question. I never timed it.

A big stone can be a substantial number of hours. Be easy for it to take 8-10 hours depending on what stone and how much you obsess over pinpoint accuracy, going back and re-touching things that no one can actually see without magnification but as the cutter you know are there and it's uncomfortable to leave them. The way I cut sapphire also requires an extra step compared to most other stones so that takes more time as well.

But I don;t think this stone took as long as I was expecting because there were no issues with polishing - it polished extremely rapidly with cerium, far quicker than I would have expected large facets to polish. Probably about 7 hours maybe?
 
Finally finished my second stone, a standard round brilliant, did a 'student cut' on a piece of 'bottlite' first, so this is the first 'real' cut. 7ct CZ :) Missed on one meet point next to the table at 6 o'clock but happy with all the others, continuous polished girdle. Finished stone is around 10mm dia so will fit a standard setting which was also one of the cutting targets set by my instructor.

1529194582_7ct-cz-2.jpg


love the colour, ....oops just noticed the fluff at 12 o'clock... cameras never lie!

Thanks everyone for the input you have offered over previous posts, it hasn't gone astray!
 
Nice work :cool: love the colour on the CZ it really pops out

How did you photograph your stone, it looks amazing on the black background.
 
Wally69 said:
Nice work :cool: love the colour on the CZ it really pops out

How did you photograph your stone, it looks amazing on the black background.
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Thanks mate, yes the stone really dances and would be quite eye-catching in a nice setting.

Photograph was taken in bright shadow with the stone facing towards the sunny area. Camera is a Panasonic GH4 with an Olympus 60mm macro lens and the exposure was set with -2EV to compensate for the very dark background which caused the stone to be over exposed. I also use multiple exposure for a short burst , 6 or so shots, and this helps reduce camera shake. Other than that just crop in Corel.

I realise this might be a fairly high end camera, but pretty much any camera could do this if you can get close focus, plus control the EV. Being able to control the EV is important so the stone isn't over exposed.
 
Might need to upgrade the iPad camera, just finished an experiment with a honey/blue sapphire bom to fit a ring I found with the detector. Thought it had some star-sapphire potential but it has ended up being twice the size needed at 5.5mm and just under 1ct.

I dont have the heart to reduce it down so will have to try another.

This is the best I can do with the iPad camera, 30 different locations and lights and plenty of cursing.

1529212677_0b0f11c7-0a77-46cc-bc02-0cfd72860164.jpg
 
Thank you Mackka and LoneWolf, really appreciate your comments.

Patience, yep I fortunately have plenty, I'm also a tenacious bugger and don't give up easily when things go wrong. Did finally give up on one as having cut the pavilion 4 times due to errors learning both cutting and the machine, the stone finally got warm and slipped in the transfer jig so was out of alignment. That was a real "Oh f*$# it!" moment.

Fortunately things have improved since then!
 
Wally69 said:
Might need to upgrade the iPad camera, just finished an experiment with a honey/blue sapphire bom to fit a ring I found with the detector. Thought it had some star-sapphire potential but it has ended up being twice the size needed at 5.5mm and just under 1ct.

I dont have the heart to reduce it down so will have to try another.

This is the best I can do with the iPad camera, 30 different locations and lights and plenty of cursing.
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Yep, there's cameras and cameras. Another thing I learnt taking the CZ shot is NEVER shoot under LED light, shade is best then halogen, but this is a different colour temperature so throws a orange cast over the shot unless you change the camera settings first.

If there are any polishing flaws, LED lighting will magnify these to an unbelievable degree. :mad: :mad:
 
Heatho said:
Nice star Wally, I've got a 30ct rough star if you want to attempt it one day. :Y: :)
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Sounds like a good challenge to throw on the table Heath. Although I will get a couple more CABs under my belt prior to tackling your hard won treasures.

Also did a 1ct blue bom that didnt star at the same time, it is quite a quick process compared to faceting and was quite surprised at the outcomes considering the rough stones I started with.
 
Looking forward to seeing how the next ones turn out mate. I think stars can be a bit hit and miss but when they turn out right they are amazing.
 
Dihusky said:
Finally finished my second stone, a standard round brilliant, did a 'student cut' on a piece of 'bottlite' first, so this is the first 'real' cut. 7ct CZ :) Missed on one meet point next to the table at 6 o'clock but happy with all the others, continuous polished girdle. Finished stone is around 10mm dia so will fit a standard setting which was also one of the cutting targets set by my instructor.

https://www.prospectingaustralia.com/forum/img/member-images/10304/1529194582_7ct-cz-2.jpg

love the colour, ....oops just noticed the fluff at 12 o'clock... cameras never lie!

Thanks everyone for the input you have offered over previous posts, it hasn't gone astray!
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Very nice stone there mate, well done :Y:

My second stone was tv - ite, now becoming scarce with the invention of flat screen tv's :)

You're well on your way :Y:
 

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