Forums Beginner Questions Competition stones and modifying design angles for different R.I.s

16 replies, 5 voices Last updated by michaelnoetzel 4 years, 3 months ago
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  • #2230

    michaelnoetzel
    Participant
    @michaelnoetzel

    I am a novice cutter (3 stones cut to my name to date), who has been learning about faceting for a couple of years. With the release of this year’s (2016) designs, I am interested in submitting a stone and am considering using a synthetic sapphire or C.Z.

    The Novice category design is called Treforze and was designed to be cut in Okenoite Feldspar which has a refractive index of about 1.52. The competition instructions indicate that the design can be cut in whatever material we choose with R.I.s from 1.52 to 2.16 without changes, but are we allowed to alter the cutting angles to optimize performance as long as we stay within the stated L/W dimensions and maintain the same meetpoint layout?

    I recently purchased GemCad and GemRay and imported the Treforze design into each program as a way to learn how to use each program. At the given R.I. of 1.52 there was a certain performance returned. But inputting 1.76 and 2.16 for Sapphire and Cubic Zirconial respectively, RayGem suggested as much as a 10 degree increase in the pavilion angles (and reduction of the crown angles by about six degrees). These changes dramatically altered the end-view appearance of the stone and even with improved performance I would not modify my own submitted stone by that much, but if we are given the freedom to enhance the design I would like to do so; again understanding that I would have to abide by the stated length/Width parameters, girdle thickness, and same general facet layout and meetpoints.

    As this would be my first competition, I am unclear to what the rules and traditional practices are in this area.

    #2231

    Alan Balmer
    Keymaster
    @alanbalmer

    You may alter the angles, so long as the plan view does not change. Click on the “Competition” link at the upper right, and you will see another link for the rules (in PDF format). You should download that and study it.

    “10.46 Plan view – That arrangement of points and lines that one sees when looking
    directly down or up the 90° vertical axis of the stone. While cutters may alter the angles
    (and therefore crown and pavilion height) of the plan, they may NOT add or subtract any
    facets from the plan view diagram.”

    Good luck.

    #2251

    michaelnoetzel
    Participant
    @michaelnoetzel

    Thank you Alan. I thought I set this post up so that I would receive an email notification if there were any responses and I haven’t seen any. Glad I checked back in to the actual post.

    #2403

    scottwkelley
    Participant
    @scottwkelley

    I just finished the novice stone using quartz clear without change, novice, and the checker board and light dispersion is very nice. The cut may look simple but the points are susceptible to chipping. Took three stones and many recuts to achieve a stone to be proud of. I will try another, maybe, if I want more frustration.

    #2405

    michaelnoetzel
    Participant
    @michaelnoetzel

    Scottwkelley: Agreed to the chipping issue. My plan on the design was to do one copy in a lab created amethyst cabachon I bought to recut as a practice run and started on the Pavillion side.

    I cut the first six facets to as good a culet as I could. I went onto the girdle and cut and polished that and went back and polished the first six facets before doing the last three on that side. When polishing the six facets I noticed some chipping on some of the edges but also a couple of spots that liked as if chips were jettisoned out of the stone.

    I don’t believe I hit the stone and am certain that they were not there a moment earlier because I was inspecting progress on this cat hair I was polishing out of the facet and one minute the surface was pristine except for the one scratch and the next thing I know I have three or four chips.

    I had already noticed several chips in tbe corners of the girdle facets that would later be cut out during the construction of the crown so I ignored them but it made me recognize that the design is prone to these chips in general. I don’t know if the specific piece if material I was cutting could have been fragile in some way but it did seem vulnerable to chipping and the most severe damage was in those three girdle corners.

    I’m still working on the crown of that first piece. I had hoped to cut it so well that I could submit it if something went wrong with the next copy I did, but I don’t trust the material now for anything other than to work out bugs and to use for my dry run.

    #2406

    michaelnoetzel
    Participant
    @michaelnoetzel

    Oh, and one last observation on the chipping was that I took a metal vernier to the stone width during the polishing of the girdle. I was using an eye loupe to make the measurement in an effort to avoid scratching the stone and saw the corner chips before the tool reached the stone.

    I adjusted the jaws to size, trying to steer clear of that part of the girdle that I hoped to save and as soon as the metal touched the stone corners I could hear this aweful creaking/grinding sound as if the stone were begging for mercy and I did create several chips taking those measurements.

    The angles are so sharp there that the corners are just fragile. So to anyone reading this thread and is interested in submitting a stone to the novice single stone competition for this year, be wary of this issue. The design itself is as it stated in the contest layout, deceptively simple but makes you focus on the basic foundation an ameture needs to master to cut a stone well. I have only cut about a half dozen stones myself and have not yet even completed my dry run stone but I wish we had just a few more facets included in the design to better make it pop. That said, the design is still fun to cut and I’m learning a lot from working on it. Good luck to anyone entering their own stones.

    #2408

    michaelnoetzel
    Participant
    @michaelnoetzel

    So, this is how my day is going …….

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    #2410

    Tom Maxwell
    Participant
    @tmax

    OUCH!!!

    #2411

    Alan Balmer
    Keymaster
    @alanbalmer

    I did a test cut in Jewelite with no issues. (I like this material for test cuts because it’s cheap, fast, polishes easily, and has a high RI).

    I’ve cut other trillions with similar point angles from various materials, so I’m not convinced it’s the design. I’m reminded of the infamous “citrine from hell” from a few years ago.

    What did you polish with? I used zirconium on a Darkside.

    #2414

    scottwkelley
    Participant
    @scottwkelley

    My chips came when sizing the girdle. Soft hand and patients is demanded on this cut. It has taught me a lot and has given me confidence to cut well. My chips were showing up after starting on the crown and girdle on the pavilion main near the corner. I blame it on me not the material or design. Rushing the cut, to much pressure possibly, but it was me for sure.

    #2432

    Tom Mitchell
    Keymaster
    @tommitchell

    Michael,

    You might also find that if you cut a stone with a much higher RI that the design, you should get a lot more dispersion than expected. For example with the novice stone design having an RI of 1.52, if you cut it in CZ with an RI of 2.15 to 2.18 you will end up with a very spectacular stone.

    Unfortunately it doesn’t work the other way around. If you cut a stone with a low RI using a design with a high RI, you will end up with major windowing or a dead center.

    Tom Mitchell

    #2435

    scottwkelley
    Participant
    @scottwkelley

    Thanks Tom, that makes sense. Do you have a good resource for a inexpensive budget to get such cutting material. And what do you use for final polish? I do like the stones design but I don’t know if I would like to set it, that would be a challenge too. Have you ever seen this cut set?

    #2694

    michaelnoetzel
    Participant
    @michaelnoetzel

    Well, my 2016 Single Stone Novice entry is finished and in the mail. I learned a lot from this competition; probably the most advancement I will ever get in so short a period of time; being the beginning stages of my new found hobby. I suffered quite a bit of heartbreak during some of the polishing phases when I’d suddenly hear that sickening sound of a particle dragging across the facet I was working on and I’d have to recut everything. I don’t even know how much time was logged into this stone, probably a couple of hundred hours, but if I had it to do over again I’m sure I could do it much faster and probably do a better job now that I’m more familiar with how the design works.

    My boss isn’t talking to me because I took three days off from work this week without giving him any advanced notice but when I brought it into work today and showed him what I had been working on I think he was genuinely impressed. He had no idea I started faceting until a couple of weeks ago when I showed him a rendition of the 2014 Novice stone (heart shaped) that I had also recently finished (just for practice) cutting in red cubic zirconia.

    I purchased a used microscope from Ebay that I had hoped to employ for this competition, but which unfortunately arrived with its articulated arm (cast iron) shattered and unusable. I’m not sure what to do with it at this point but will likely try to rig up something that will allow me to use it to check my work in the future, but for this stone I was relegated to an eye loupe and tried to take my time to find any flaws. Several herringbone patterns reared their ugly heads that would only be seen with the light shining at specific angles but I think I got them all. I also had the opportunity to work with several different polishes and laps, which was kind of fun. At the low end of the spectrum I used 14K Voodoo polish (meaning most coarse, not cheap quality) which I really LOVE, and went all the way up to 200K Blakstik for a while. Honestly, I couldn’t tell the difference between the two differences (I think I used five different products).

    My prepolish lap was a 3000 grit Crystalite lap and for polishing I used a variety of laps including a Darkside, BA5T lap, BATT lap, and a Crystalite ceramic lap. I have tried the ceramic lap on each of the 6 or 8 stones I have cut so far, hoping I could find joy because I keep hearing about how good they polish once you get used to them. I got better results with this stone with it but also got far more instances of scratching with it too. I keep hearing that people put on too much polish and that’s why they scratch. Toward the end all I did was to wave the container of polish into the general proximity of my Facetron machine but apparently even that was too much – LOL. There was a point when I was literally using just straight water from the drip tank with periodic spraying of filtered water when necessary and I actually did get decent results with that method.

    Anyway, Here is my finished stone. It is synthetic sapphire and weighed in at 3.14 carats. When I first dopped it, I didn’t like the color and planned on using the material as a practice piece. Then I polished the first facet and it started to glow! It actually looked like it was on fire and before long I started paying much closer attention to each facet, ‘just in case’ I decided to use it for my entry. In short order it took center stage in my efforts. I think it looks really good if you stand back about three feet and squint your eyes, you can hardly see its flaws 😉

    Good luck everyone.

    BTW, does anyone know when the judging actually finishes?

    #2696

    michaelnoetzel
    Participant
    @michaelnoetzel

    This is the stone.

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    #2698

    Tom Maxwell
    Participant
    @tmax

    Hi Michael,

    Congratulations on your first competition stone! You will benefit greatly from just gong through the process and getting the evaluations of the judges.

    The timing of releasing the scores depends a lot on the number of stones submitted and the time for the judges to properly process and score the stones. The scores are usually posted in the September Newsletter. There are several more days before the deadline with more stones arriving daily. You will just have to be patient.

    Tom Maxwell

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