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 Post subject: Sapphire faceting for a beginner?
PostPosted: Fri Dec 03, 2021 1:23 pm 
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I'm in the early stages of learning faceting, have finished 10's of stones with decent success, mostly with quartz-class rocks. I have a Graves faceter. My daughter is getting married next fall and she's asked if I could facet a sapphire to match her engagement ring for a necklace. I'm willing to give it a go, even with my limited experience and entry-level machine. So, two questions for the experienced folks out there:

1. Where is a good place for me to buy some decent sapphire rough to work with? Her ring is fairly dark blue. I'd need something big enough to look good in final form as a necklace.
2. Any recommendations for a diagram, not too complicated, for a teapdrop/pear shape? There are, of course, lots of resources on the web and I'm sure I could find something, but an experienced recco is always nice.

I'm thinking I'll get a piece of amethyst of similar size to try the diagram first before working with the more expensive and harder sapphire.

Thanks!

Greg


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 Post subject: Re: Sapphire faceting for a beginner?
PostPosted: Sat Dec 04, 2021 10:16 am 
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I'm doing something similar, my wife wants to replace the stone in her wedding ring with one I cut.

First question, natural sapphire or lab sapphire? If natural, how big of a stone do you want to cut? Be prepared to spend literally thousands of dollars on a piece of natural rough that can cut a clean, large stone. I spent a lot of time going back and forth with both Milstead Gems and Cyrus Rough before I settled on a 11 carat piece of rough (that I think I can get a 2+ carat stone from).

If you're open to lab created sapphire, you can cut a gorgeous stone of pretty much any size & color you're interested in.

Assuming you're going with natural rough, I would hold off on picking the exact faceting pattern until you have the rough in hand. The rough I got is well shaped for a triangular stone, so I'm going with Arya's Frost Giant pattern.

I plan on cutting the pattern at least twice in lab sapphire as practice. I've found sapphire cuts and polishes easily. I'm cutting with a sintered 600, pre-polish with 3K Pandamonium on a BA5T, and polishing with 100K Pandamonium on a Diamatrix (all laps & polishes from Gearloose).

Once you get your rough, if you need some lab sapphire to practice on, PM me and I'll be happy to send you some.

Good luck!


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 Post subject: Re: Sapphire faceting for a beginner?
PostPosted: Sat Dec 04, 2021 3:20 pm 
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If your truly going to cut a sapphire in the end, amethyst is not your practice material. Like previously stated use a synthetic sapphire. There is no need to test the diagram, what will that achieve. Performance of a cut is mostly in the gemstone and diagrams are designed around refractive indexes. There are many variables to take into account. Keep in mind a synthetic gemstone is created without what mother nature throws into the the natural counter part, no matter how slight it may be.
Find your rough with this mind.
30% -40% final yield, most likely this will be the best expectations. Clarity, color saturation, color zoning and more.
Your budget for rough will dictate the quality and color of corundum you will ultimately get. Learn a bit about evaluating rough, the shape of rough will almost always direct you to the final shape it wants to be or should be for best yield. Cutting by diagram in most cases lead to lower yields in Brilliant style designs. The more experienced cutters can evaluate the rough in these cases to get better yields.
The machine your using does not control the quality of your cutting, you do.
Believe me when I say, if your best part life partner is like most all others, she will be happy if you were to cut her natural sapphire in a nice optimized round. 6-9mm as the center stone, and cut some smaller stones to frame it. As you gain more experience go for the more complicated when your working with expensive rough, but if you have an open ended budget, forget all of this. :) Have a happy day faceting.

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 Post subject: Re: Sapphire faceting for a beginner?
PostPosted: Sat Dec 04, 2021 7:45 pm 
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The first thing we need to see is a good picture of the sapphire you are trying to match. We can then determine which type/origin of rough sapphire you need to source.

Once we know this we can properly estimate cost and availability.

Post a few well lit pictures and we will be happy to help.


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 Post subject: Re: Sapphire faceting for a beginner?
PostPosted: Sun Dec 05, 2021 9:51 am 
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I disagree about the test cutting -- unless it is a dirt simple pattern, you don't (as a novice) want the first time you try a pattern to be on a $3000 rock.


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 Post subject: Re: Sapphire faceting for a beginner?
PostPosted: Sun Dec 05, 2021 3:03 pm 
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@loydb Why? In your case your talking about a design by Arya, a well established gem designer and cutter. Cut the design as instructed.
As far as @tanstaafl with 10's of stones completed with as stated success, not a novice but an intermediate with some apprehension to conquer gems other than quartz.
1. Where can @tanstaafl buy sapphire rough? Hard to say, Tucson is on the near horizon. Online? Finished carat weight expectations, color designation, locality origin.
2. As far as a pear design for a sapphire already optimized for a RI 1.76 and not 1.54, Van Sant designs are all designed for corundum. Some of them online may have been tangent ratio scaled for 1.54. Cutting medium to dark sapphire in a design with angles for quartz will most likely achieve a ink blue gem with no life. You can tangent any design to your liking, but some designs that have extremely small facets at the refractive index orignally designed say quartz and then tangent the design down these facets can become almost non existent. Gram has a couple of designs in pear shapes that will work, Long & Steele meet point diagrams have alternate angles for many of there designs, online no mostly for quartz.

There are Pitfalls in all thinking whether you agree or not.

Not going to entertain your dirt simple comment. There is no fight here.
Your entitled to your opinion, as am I.
:) Have a great day faceting.

Like @1bwana1 said some pics of what your looking to achieve, finished size, budget!!! would be helpful when sourcing rough.

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 Post subject: Re: Sapphire faceting for a beginner?
PostPosted: Mon Dec 06, 2021 11:34 am 
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Awesome replies, thanks so much. I'll be seeing my daughter at Christmas, so will post some pictures then. Until then, I bought a couple of raw stones off ebay to practice with (perhaps destroy!). I'll look forward to hearing reccos for higher quality stones after I post some picture of the engagement ring.

I also really like the suggestion that I mount a sapphire surrounded by other stones - I'll see if I can locate a finding for something like that. I've been buying findings from Rio Grande, but don't know if they have something close.

I'm starting to get excited about getting something cut, but I am glad the wedding is 10 months or so off...

Greg


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 Post subject: Re: Sapphire faceting for a beginner?
PostPosted: Mon Dec 06, 2021 11:34 am 
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It's not a matter of the design being good/bad. It's a matter of being sure that I know how a tier cuts in. I've more than once realized I was going for the wrong meet location or something. Granted, the cutting assistant feature on GCS has made this *much* less likely, since I can pre-viz the cut using it. But the feeling of "Oh crap, that's the wrong placement for that first facet of a tier" would be devastating with a piece I've paid so much for. If you're experienced enough that you never make mistakes on a pattern, good for you. I've only cut around 70 stones, I absolutely want a trial run at something like that.

I'm not trying to fight about it, I'm just trying to explain why I'd do something that you're obviously dismissive of.


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 Post subject: Re: Sapphire faceting for a beginner?
PostPosted: Mon Dec 06, 2021 1:42 pm 
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If it is a dark blue stone as originally described being matched, your facet pattern choices will be limited.

We still need a picture.


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 Post subject: Re: Sapphire faceting for a beginner?
PostPosted: Mon Dec 06, 2021 2:19 pm 
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loydb wrote:
It's not a matter of the design being good/bad. It's a matter of being sure that I know how a tier cuts in. I've more than once realized I was going for the wrong meet location or something. Granted, the cutting assistant feature on GCS has made this *much* less likely, since I can pre-viz the cut using it. But the feeling of "Oh crap, that's the wrong placement for that first facet of a tier" would be devastating with a piece I've paid so much for. If you're experienced enough that you never make mistakes on a pattern, good for you. I've only cut around 70 stones, I absolutely want a trial run at something like that.

I'm not trying to fight about it, I'm just tying to explain why I'd do something that you're obviously dismissive of.

Appreciate you answering the why.
Tip for not seeing where the meet is going to hit first is to magic marker the finished tier, then the eye can follow the current facet being cut. Finish the tier then marker this tier. You do not have to do every tier, but just the ones your unsure of.
Hope that helps some.

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