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 Post subject: Faceting Emerald caused darkening on the inside
PostPosted: Wed Nov 08, 2017 5:34 am 
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Hello,
First time faceting a small emerald. Highly included.
Problem became obvious after a prepolish. It looks as if the brown leftover goo while faceting has somehow penetrated the emerald and now there are dark lines going through the emerald.
I can only speculate that there were hollow grooves through the stone and they sucked the brown slurry. Now am left with these dark lines inside the emerald.

The question is, is this something that often happens? How to prevent it or fix it ?

Will try to post some pictures some of you with more experience may have seen thiz already.
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 Post subject: Re: Faceting Emerald caused darkening on the inside
PostPosted: Wed Nov 08, 2017 11:22 am 
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Brown slurry from an emerald?

Please describe your technique in detail and provide a photo of the emerald.

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 Post subject: Re: Faceting Emerald caused darkening on the inside
PostPosted: Thu Nov 09, 2017 1:56 am 
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A common problem in cutting emeralds is swarf lodging in flaws in the stone.
Use of oil in pre-polish or polish nearly always makes the situation worse.
I use water only on a Twister 8000 lap and the same with 50k on a Greenway lap to avoid this problem.


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 Post subject: Re: Faceting Emerald caused darkening on the inside
PostPosted: Thu Nov 09, 2017 4:39 pm 
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TOM KIDWELL wrote:
I use water only on a Twister 8000 lap and the same with 50k on a Greenway lap to avoid this problem.


The Twistor used 1800 mesh grit. The drawback of polishing emerald with the Greenway are minute particles of chromium oxide lodging in the cracks which are difficult to fully remove. If you were to get the emerald certified by GIA with those Chromia particles in the stone, you could expect it to be reported as treated.
A much better alternative for polishing emerald is the Skyway lap. The particles are easier to fully remove and a fine polish occurs quickly. No diamond necessary.
BTW, the Twistor2 will use 1500 mesh diamond in double the Twistor concentration, double the thickness of diamond layer, harder surface, and with the FFC water soluble lubricant, provide a finer finish than the Twistor.

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 Post subject: Re: Faceting Emerald caused darkening on the inside
PostPosted: Fri Nov 10, 2017 12:58 pm 
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Any idea when the Twister2 will be available? I like the concept of these laps with a built in charge, however, almost all after a few stones are pretty useless, and way too slow. I use my Twister, which so far has been the best of the ones I have tried sparingly so as to not wear it out too quick.

For stones like emerald or other included stones, these are certainly the way to go to avoid forcing sludge into the exposed inclusions.

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 Post subject: Re: Faceting Emerald caused darkening on the inside
PostPosted: Fri Nov 10, 2017 4:09 pm 
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Precision Gem wrote:
Any idea when the Twister2 will be available? I like the concept of these laps with a built in charge, however, almost all after a few stones are pretty useless, and way too slow. I use my Twister, which so far has been the best of the ones I have tried sparingly so as to not wear it out too quick.
For stones like emerald or other included stones, these are certainly the way to go to avoid forcing sludge into the exposed inclusions.

The correct spelling is T-W-I-S-T-O-R
Use Lava Soap to dress it and you will notice it cuts faster.
The first lot of Twistor2s will ship mid-December.
I will have more available in late January.
Using the FFC dilution in the drip tank, I cut facets on a Citrine with the Twistor2 prototype and the finish was very similar to that of 8000 mesh diamond on BATT. The finish produced on the 9M metal bonded diamond wheel with FFC dilution was slightly finer than 3000 mesh diamond on BATT.

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 Post subject: Re: Faceting Emerald caused darkening on the inside
PostPosted: Sat Nov 11, 2017 1:22 am 
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thomas.adamas wrote:
BTW, the Twistor2 will use 1500 mesh diamond in double the Twistor concentration, double the thickness of diamond layer, harder surface, and with the FFC water soluble lubricant, provide a finer finish than the Twistor.
Thomas - How do performance, finish, and lifetime of the Twistor2 compare to a 3000# sintered bronze lap?


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 Post subject: Re: Faceting Emerald caused darkening on the inside
PostPosted: Sat Nov 11, 2017 2:21 am 
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Duncan Miller wrote:
thomas.adamas wrote:
BTW, the Twistor2 will use 1500 mesh diamond in double the Twistor concentration, double the thickness of diamond layer, harder surface, and with the FFC water soluble lubricant, provide a finer finish than the Twistor.
Thomas - How does performance, finish, and lifetime of the Twistor2 compare to a 3000# sintered bronze lap?


I have never used a 3000 mesh bronze bond diamond wheel for the life of the wheel.

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 Post subject: Re: Faceting Emerald caused darkening on the inside
PostPosted: Sat Nov 11, 2017 4:45 am 
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Not slurry, wrong lingo. I meant swarf, it seem to have been sucked by the emerald into thin lines through the crystal (growth tubes?) I was cutting using 3000u grit diamond on copper ap.

I am just a beginner at this using crude tools. Before you cringe, let me just alleviate it by saying i am only sacrifing rough a little bit better than a stone from the road

Heres is a picture of the pavillion on a baguette type design. Tubes filled with swarf running on C axis which is also the long axis of the baguette.


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 Post subject: Re: Faceting Emerald caused darkening on the inside
PostPosted: Sat Nov 11, 2017 6:06 pm 
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The brown goop is a mixture of copper powder, diamond, and whatever liquid you used on the lap. Without vacuum equipment, I would suggest soaking the material is warm water with some detergent.

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 Post subject: Re: Faceting Emerald caused darkening on the inside
PostPosted: Sat Nov 11, 2017 9:49 pm 
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Got it.
And so, to avoid this in the future, should i use water instead of oil for lubrication of the diamond or are these type of rough with growth tubes running through just better to avoid?

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 Post subject: Re: Faceting Emerald caused darkening on the inside
PostPosted: Sun Nov 12, 2017 6:16 pm 
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I recommend you do not use a charged copper lap. A metal bonded diamond lap for faceting would be better.

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 Post subject: Re: Faceting Emerald caused darkening on the inside
PostPosted: Sun Nov 19, 2017 12:11 pm 
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thomas.adamas wrote:
Precision Gem wrote:
Any idea when the Twister2 will be available? I like the concept of these laps with a built in charge, however, almost all after a few stones are pretty useless, and way too slow. I use my Twister, which so far has been the best of the ones I have tried sparingly so as to not wear it out too quick.
For stones like emerald or other included stones, these are certainly the way to go to avoid forcing sludge into the exposed inclusions.
The finish produced on the 9M metal bonded diamond wheel with FFC dilution was slightly finer than 3000 mesh diamond on BATT.


It is very ineteresting!!! It is the way for faceting Emeralds!!!

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 Post subject: Re: Faceting Emerald caused darkening on the inside
PostPosted: Sun Nov 19, 2017 1:07 pm 
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Thomas,

What is the FFC dilution?

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