Here are a couple more citrines cut with concave facets on the pavilion where the mandrel was at an angle.
The first is 9.77 carats and measures 18.8 x 10.3 mm.
The second is 10.85 cts, 21.1 x 9.0 mm.
I will be heading off to Tucson in a few more weeks. Meanwhile I will be working on finishing off rough acquired in 2018. Only a dozen pieces left. But some are rather large so odds are, There will be some of them waiting for me when I return home.
Here is my first attempt using my new Ultra Tec Fantasy machine for something other than straight on concave facets.
This is a 9.49 carat lemon citrine which measures 14.9 x 10.8 mm.
Pictured below is a 10.41 carat, 12.9 mm. colorless topaz that was one of the batch of stones that I cut over the past few weeks while I was getting familiar with using my new UltraTec Fantasy machine to cut concave facets.
Most of the work was done with rose quartz which is not the most exciting material. However, the price is right for the practice situations where you expect that major errors are likely. And they did happen. I learned that timing is important when bringing down the stone to the mandrel as unlike the OMF where only the mandrel is moving in and out, with the Fantasy machine, the entire tool drive moves. I was not paying attention and collision with the slash guard took off a big chunk of the pavilion in one instance. Needless to say, lesson learned.
Now I have a more colorful and varied batch dopped up and ready to go for the next phase where I start exercising some of the options of the fantasy machine which go beyond what I had with the old OMF.
I am also getting used to being back in my workroom. We moved things around for remodeling a couple years ago and somehow just never got back until a new piece of equipment provided extra motivation.
Here is the first stone cut using the new fantasy machine. It is a 12.1 mm., 7.11 carat rose quartz hexagon with concave facets on both pavilion and crown.
For faceting demonstrations at the local club shows, I typically want something that is big enough for visitors to see, but inexpensive enough that I won't be upset when working in less than ideal conditions (distractions!) results in mistakes. Lemon citrine and rose quartz seem to be what I end of choosing for these situations.
Since I had a number of pieces of rose quartz pre-formed from a chunk I acquired for just that purpose last year from Steve Ulatowski / New Era Gems, I am working with that for the "learning experiences" I know I am going to have getting used to new equipment and cutting options. It was a good choice -- on this piece I had several "oops" happenings ranging from rolling off the mandrel (had it turning the wrong way) to running off the end of the mandrel (did not check the mast position adequately).
After many years of using the Polymetric OMF for cutting concave facets I have taken the big step to upgrade to the ULTRA TEC Faceting Fantasy machine.
Until recently I thought the only option would be to swap my Fac-Ette GemMaster faceting machine for another brand, like Ultra Tec which was compatible with the fantasy machine. Then I found out that the folks at Ultra Tec have devised an option to adapt the fantasy machine for the Fac-Ette GemMaster.
This is their first Fac-Ette (default) left mast version. I am looking forward to the faceting options that this machine will open -- once I learn and get up to speed on the features it offers.
This 7.44 carat, 11.5 mm. gem is the last of my ametrine parcel purchased from Steve Ulatowski / New Era Gems last February in Tucson.
It was another experiment to see if the gold / purple color break could show up and still have a stone that sparkles and glows.
The camera shows the color variation better than it appears to the eye.
This stone was as much for fun as for anything else. It is a 8.47 carat prasiolite, 13.2 mm.in diameter. The pavilion had a row of narrow concave facets splitting the normal culet row facets. Then the crown was rounded up to the table instead of using rows of flat facets. Finally a number of concave facets were added to the crown.
The cameral once again sees things the do not quite match what I see. The pattern in the center is not something that I "see". and the light and dark pattern is much more subtle.
Here is a 5.97 carat ametrine which measures 10.4 mm. across. In an experiment to see if the two colors would show rather than mix, I tried using concave facets on two sides of the pavilion to make it really bright, and using steep angles on the other two sides (similar to a method used for closed C axis tourmalines.)
It seemed to work somewhat. As usual, the camera showed the difference more than it seemed to me. And also added a bit an impressionist painting look to the stone.
Pictured here is a new 5.44 carat, 11.0 mm. prasiolite. As mentioned previously, I find the hexagon cuts attractive. Here the light and dark patterns from the concave facets used on the pavilion of the stone are much more obvious to the camera than to my eyes. The result reminds me of an iris flower (another favorite of which I have too little in my garden.)