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 Post subject: Re: Off the dop - post YOUR latest creation
PostPosted: Sun May 26, 2019 9:42 am 
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I've abandoned faceting diagrams over the last bit so I might find some heuristic rules for "improv gemcutting". Both these stones are recuts where I didn't use a diagram, and avoided even jotting down a single angle or index position at any point


Attachment:
20190526_093928.jpg
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The green zircon is 2.14 ct and was fully recut (also had to remove a serious flaw). The table is purposefully not cut to full depth to create an impression similar to a single row of step facets around the table without actually cutting them. I think that worked out reasonably well.


Attachment:
20190525_060520~2.jpg
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The pink tourmaline is 4.05 ct, and only the pavillion was recut (to close a windshield sized window). The pavillion was originally a portugese style. I retained the row closest to the girdle, which served as barion-esque facets to adapt the shape of the pavillion I cut to the rest of the stone. Looking at the plain-jane crown, I somewhat regret not recutting the whole thing.

Photos taken with a Samsung S8 cellphone outside


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 Post subject: Re: Off the dop - post YOUR latest creation
PostPosted: Sun May 26, 2019 5:06 pm 
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Well done!

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 Post subject: Re: Off the dop - post YOUR latest creation
PostPosted: Sun May 26, 2019 7:57 pm 
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Faceting took a backseat for a while to spring cleaning and garden chores. Since I was doing a demonstration at a local rock show in April, I dopped a dozen pieces of quartz in the 10 to 15 mm range to have something big enough for folks to see. Once the show was over, I had these to conduct experiments with the fantasy machine. (I am attempting to learn how to use it with tools other than the concave mandrels.) Finally worked through the batch and here are a few of them.

Smoky quartz, 4.48 cts, 10.2 mm. with normal concaves on the pavilion and an apex crown.
Attachment:
1720.JPG
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Lemon Citrine, 6.69 cts., 12.1 mm., using the slitter tool to make small muiti-concaves on the pavilion.
Attachment:
1717.JPG
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Smoky quartz, 5.13 cts., 10.8 mm., variation similar to above
Attachment:
1723.JPG
1723.JPG [ 47.27 KiB | Viewed 592 times ]



Did I mention I like hexagons?

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 Post subject: Re: Off the dop - post YOUR latest creation
PostPosted: Tue May 28, 2019 11:12 am 
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Beautiful work, Mary!


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 Post subject: Re: Off the dop - post YOUR latest creation
PostPosted: Wed May 29, 2019 9:09 am 
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Mary,

Those are stunning by themselves, much more with the fantasy cutting you added. Absolutely beautiful :)

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 Post subject: Re: Off the dop - post YOUR latest creation
PostPosted: Thu May 30, 2019 6:51 am 
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Mary: Are the concave surfaces cut with the stone oriented towardd the same centrepoint as the culet, and use the same angles as the facet you are adding them to with a slightly increased depth? Or are things oriented differently once you move over to concave.

It's really great to see some side-by-side shots like that to help understand the optical effects. Lovely stones.


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 Post subject: Re: Off the dop - post YOUR latest creation
PostPosted: Thu May 30, 2019 10:47 pm 
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thresh wrote:
Mary: Are the concave surfaces cut with the stone oriented towardd the same centrepoint as the culet, and use the same angles as the facet you are adding them to with a slightly increased depth? Or are things oriented differently once you move over to concave.

It's really great to see some side-by-side shots like that to help understand the optical effects. Lovely stones.



Typically for simple concave facets I will use the pavilion angle or something slightly more. The axis of the cylinder runs in the same direction as a line from the culet to the girdle. For the stone pictured I probably used 8 mm. mandrels. I do not cut deep. I have learned that just a little curve makes a huge difference. (I have also discovered that too much turns into a negative. Hope to have more on that one of these days.)

For the others, I am learning with the some other tools. In this case it is the "slitter" tool that comes with the Ultra Tech fantasy machine. It appears to be a v-groove mandrel, but I have probably blunted it in my trial and error and it appears more like a compound concave. The axis of rotation is turned 90 degrees from what was done with the standard concave mandrel. It has a diameter about an inch in one direction (used for cutting in the culet to girdle direction) and only a small fraction in the other direction. So far, I have been cutting with the mandrel static until the length of the cut is satisfactory. It is going deeper than I would consider with a cylinder mandrel.

The result is very different. It looks to me as if the grooves go a lot deeper into the stone than they actually are. Not sure how much of that is due to the polish not being as good -- still working on that!

Have a couple other mandrels to try. Also should see what happens when the compound concave grooves are kept more shallow like with the cylinder mandrels.

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 Post subject: Re: Off the dop - post YOUR latest creation
PostPosted: Wed Jun 26, 2019 11:53 am 
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Apparently I can't read and posted in the wrong thread (posted in before and after). Here are my recent cuts.


An unfortunately included and poor saturation bicolour tourmaline... where I also accidently didn't cut the c-axis oriented facets deep enough to avoid colour mixing,


Garnet (with a 1.72 RI) with a Superman's decal-ish outline,

Aqua with a pope-hat/motorboat outline,

Aqua (not new) in a elongated trillion

Green zircon,

Pink tourmaline, pavillion only recut,

Lithium Tantalate barion cushion,

And a bicolour tourmaline that will probably be joining the fish gravel soon LOL

Attachment:
20190626_075800.jpg
20190626_075800.jpg [ 2.45 MiB | Viewed 228 times ]


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 Post subject: Re: Off the dop - post YOUR latest creation
PostPosted: Fri Jun 28, 2019 10:10 am 
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thresh wrote:
Apparently I can't read and posted in the wrong thread (posted in before and after). Here are my recent cuts.


An unfortunately included and poor saturation bicolour tourmaline... where I also accidently didn't cut the c-axis oriented facets deep enough to avoid colour mixing,


Garnet (with a 1.72 RI) with a Superman's decal-ish outline,

Aqua with a pope-hat/motorboat outline,

Aqua (not new) in a elongated trillion

Green zircon,

Pink tourmaline, pavillion only recut,

Lithium Tantalate barion cushion,

And a bicolour tourmaline that will probably be joining the fish gravel soon LOL

Attachment:
20190626_075800.jpg


very nice designs and nice collection.

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 Post subject: Re: Off the dop - post YOUR latest creation
PostPosted: Sat Jun 29, 2019 11:13 am 
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My second attempt at faceting cerussite, a 75 ct, 18 mm square stone in a slightly modified Squartuguese (designed by Marco Voltolini) for a client. Cerussite is lead carbonate, extremely brittle, with extreme heat sensitivity, two directions of cleavage, and a hardness of 3 1/2. This stone has some peripheral inclusions, and a cleavage crack that threatened to split the stone, but then mostly closed up again, 'self healing' overnight, which is mysterious. I am not the only person to notice that cerussite can do this (see 'Faceting the Good the Bad and the Ugly in Rare Gems by John Rhoads' http://www.attawaygems.com/NMFG/Program_Speaker_John_Rhoads_on_Rare_Gems.html). Polishing had to be directional to avoid chipping and scratching because of the cleavage. The result is quite spectacular, especially in sunlight, because of the extreme dispersion.
Attachment:
Cerussite 75.42 ct shrunk.jpg
Cerussite 75.42 ct shrunk.jpg [ 219.14 KiB | Viewed 110 times ]


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 Post subject: Re: Off the dop - post YOUR latest creation
PostPosted: Sat Jun 29, 2019 11:23 am 
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Well done, Duncan! This looks spectacular! I hope I can see it in real life on Saturday?

Martine


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 Post subject: Re: Off the dop - post YOUR latest creation
PostPosted: Sat Jun 29, 2019 11:27 am 
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Duncan Miller wrote:
My second attempt at faceting cerussite, a 75 ct, 18 mm square stone in a slightly modified Squartuguese (designed by Marco Voltolini) for a client. Cerussite is lead carbonate, extremely brittle, with extreme heat sensitivity, two directions of cleavage, and a hardness of 3 1/2. This stone has some peripheral inclusions, and a cleavage crack that threatened to split the stone, but then mostly closed up again, 'self healing' overnight, which is mysterious. I am not the only person to notice that cerussite can do this (see 'Faceting the Good the Bad and the Ugly in Rare Gems by John Rhoads' http://www.attawaygems.com/NMFG/Program_Speaker_John_Rhoads_on_Rare_Gems.html). Polishing had to be directional to avoid chipping and scratching because of the cleavage. The result is quite spectacular, especially in sunlight, because of the extreme dispersion.
Attachment:
Cerussite 75.42 ct shrunk.jpg


beautiful cut.

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 Post subject: Re: Off the dop - post YOUR latest creation
PostPosted: Sat Jun 29, 2019 11:46 am 
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I'm not seeing your upload.


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 Post subject: Re: Off the dop - post YOUR latest creation
PostPosted: Sat Jun 29, 2019 12:03 pm 
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Barbra Voltaire wrote:
I'm not seeing your upload.
Is this addressed to me? In which case, I am puzzled. Others see the uploaded image, and the URL link works when I click on it in my message, and also when I copy and paste it into the browser. What's the problem?


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 Post subject: Re: Off the dop - post YOUR latest creation
PostPosted: Sat Jun 29, 2019 8:32 pm 
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Oops Duncan...I was confused.
I saw the copied link in Dor's post with no image attached.
Everything is OK. :oops:


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