Sneaky Gems.

Thought I'd start a little thread for my stones instead of hijacking the main "show and tell" topic all the time. If you see a design you like send me a PM and I'll shoot the diagram to you. Some of them are my own designs though and these ones I'd rather keep to myself. Mostly because they haven't been thoroughly tested and the last thing I want is for someone to destroy a nice stone using one of my designs.

First one is a gorgeous little light pinky/purple 0.435 carat zircon from Inverell. The lighting isn't ideal to show the colour of the rough behind it which is actually more intense than the piece I cut. Rough weighs 3.654 carat.

Six point asterisk design. Its actually an optical illusion as there is only 3 tiny facets on the edges of the pavilion mains. The facets reflect themselves at 180 degrees to create the illusion. Angles have been changed and one facet sequence has been removed from the crown to adapt the design for zircon R.I. Leaving this sequence in would result in cutting that particular crown sequence at angles less than 15 degrees which is a deal breaker for me. Also it had a negative effect on the yield.

Do you set any of your stones at all?
You have been doing some beautiful work, do you use gemcad for your designs? I have been teaching myself a little, but mostly just altering designs to suit different R.I.
Please keep posting, you and Lefty are both an inspiration when it comes to some of the work you have done :Y:

SC
Nice stone, looks well cut. Did you have any problems with the Cleavage Plane? I recently cut a blue and a clear - had no problems with the blue but must have set the clear at the cleavage plane and found it scratched and balled when polishing - had to re-dopp to about 5 degrees off the CP then had no further problems. What are your thoughts on CP issues with topaz?

I have a Jeweller who sets some of them set for my fiancee. I would like to do it myself and am playing around with wax carving for casting metals. But to be honest, I barely have enough time to facet let alone teach myself the intricacies of jewellery making. Its just easier to go to a Jeweller to have them done.

I use Gemcad. There are other types of software out there but I prefer it because it is such a 'slim' design. No bull and it does exactly what it is supposed to do. I still haven't completely worked out the entirety of the program yet though.

GemRay is the sister program to GemCad. It does the ray tracing and gives some idea of what the stone will look like once cut. Also helps to get the perfect angles for any particular design. However, I would er on the side of caution when copying angles directly from GemRay. Some of the suggested angles are really hard to do and produces extremely flat crowns. Especially if you are trying to adapt a low R.I design for a high R.I material.

Often times extra facets need to be added to counteract that result.

Looks very nice Sneaky.
Mackka :Y:

Here's my recent efforts with Topaz
Blue - 6 point star
Clear - round brilliant

Very nice there SC :Y: Did you leave the facets that form the asterisk frosted?

What are your thoughts on CP issues with topaz?

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Hi Moth. I can't speak for SC but I really like topaz - but I have had a few stones that gave me grief, regardless of the fact that I was well away from the basal cleavage. I've heard some people say that the occasional piece of topaz can have patches with a bit of a random crystal grain direction. I don't know if that's actually the case but I've had a couple that just did not want to take a good polish in areas that seemed well away from the cleavage plane. In the end it just took patience, persistence and a lot of swearing and cursing to obtain an acceptable polish.

Nice stones there Moth - that shade of blue is my favourite in topaz. The London blue colour has a synthetic look to me, as I found out later the stone is natural but the colour has been enhanced through irradiation.

I like that natural pale blue shade, like blue ice

Left, I polished the facets. 100,000 grit normally. I'm not sure if the effect would still work if they where frosted. I will have to try on a piece of quartz.

I love topaz but I have had a lot of issues with polishing as well on certain stones. Cutting dead on the C axis doesn't seem to be a problem neither does the m axis (directly side on). Once the cut starts going in varying angles from these two planes then problems can occur. That's my understanding/experience anyway. (more than happy for someone to educate me if that's wrong)

Yeah, I finish topaz with 100,000 as well, usually on a Matrix. I don't recall I ever had much success using alumina. Topaz is pretty hard stuff.

Many of the pieces of topaz I have are crystals from Mount Gibson, so they are still shiny and sharp-edged and not weathered and rounded like a lot of the O'Briens creek stones seem to be. I've cut plenty of the crystal points straight down on the m axis, the shape perfectly suits one of my fave designs, Jack Rowland's "Arrow". It's a beautiful design and the reflection patterns really stand out in pale blue topaz. I've never had any problems from cutting it this way. Just the occasional stone misbehaves but you can experience that with pretty much any natural stone I think.

I polish with 50,000 on a steel lap then follow up with100,000 on an aluminium lap. I seem to have problems recognising the CP though.

Listening intently on these subjects

ray

I use 8" BATTS for 3000# pre-polish, 14000# polish, then straight to 100,000# on a 6"BATT. One thing with BATTS though, the factory finish is terrible so I take mine straight to our local engineer and have him re-surface it dead flat before I even use them. I just recently got a new 6" to try with 600# cutting compound but I wasn't happy with the results. I might have to grind a few peices of junk sapphire down to set the diamond in the alloy propperly.

:Y:

Moth said:

I polish with 50,000 on a steel lap then follow up with100,000 on an aluminium lap. I seem to have problems recognising the CP though.

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It's easy to know where it is if you have a recognisable crystal. Even if a little weathered, if you can see the shape of the crystal it lies directly across the cross-section - a bit like slicing up a carrot. You can sometimes see little cracks and inclusions that are running perfectly parallel to one another, that's the direction of cleavage.

SneakyCuttlefish said:

I use 8" BATTS for 3000# pre-polish, 14000# polish, then straight to 100,000# on a 6"BATT. One thing with BATTS though, the factory finish is terrible so I take mine straight to our local engineer and have him re-surface it dead flat before I even use them. I just recently got a new 6" to try with 600# cutting compound but I wasn't happy with the results. I might have to grind a few peices of junk sapphire down to set the diamond in the alloy propperly.

Click to expand...

Gearloose normally makes good laps - though I have to say that the first BATT I got couldn't be run at any speed because it was out of balance and I had to exchange it. No machining defects were visible, Rough2cut suggested it could be a metal density issue and Gearloose agreed this could well be the case. The new one was much better and I still use it.

Back on the topaz again. My eyes needed a break from all the tiny little zircons.

2.94 carat rutilated topaz from O'Brien's Creek. Also managed an injury whilst dopping this one. Searing hot wax landed on my finger and without thinking i peeled it off straight away. Took all my skin with it too.

No pain no gain.

Nice gem mate, that's a beauty.

Shame about the finger, the stone looks great though.

I have only used epoxy so far for dopping, but have been looking at wax. Beside the burnt fingers do you have any problems using wax?

Thanks guys. Biggest issue with wax is the transfers. It is extremely easy to over heat the gem and loosen the wax on the crown side dop. Once that happens re-aligning the facets to cut the crown can be a huge problem. Especially with machines that take keyed dops. One other issue is also the excess wax on the stone can bog down on the lap when cutting tight stones and can hold heavier sized grit from the polish before which may lead to contamination of finer grit sizes. Just takes a bit of practice and experimentation to work it out. Other than that, dopping is relatively easy and very fast. Also it is really easy to change the orientation if need be.