I spent the past weekend at the San Luis Obispo Gem and Mineral Show demonstrating faceting. The club had acquired a faceting machine this year and it seemed appropriate to put it to use at the show. In preparation I had dopped up a number of decent sized garnets to use for the exercise. In addition, I brought along some finished stones to show off as well as the Vargas and Herbst books on faceting.
As expected, almost no one had any idea how faceted stones were done. There were a few folks who had some experience with cabochons, had a friend who did faceting, or did metalwork, but only one person indicated they had done any faceting themselves. One of the most frequent questions was how the stones were attached to the dops. I use superglue, so it is easy to understand why that kept popping up. Wax or epoxy dopping would have been a lot more obvious.
It was fun explaining faceting and the machine to the show attendees. Some of the kids were great. For a while I had a four year old helper working the water spray bottle for the polishing process. He definitely got into it and stayed focused until his mother finished a purchase across the aisle and came to get him. Perhaps a future faceter?
I have always had a weak spot when it comes to garnets. It probably started when I was very young and my mother told me that her birthstone was garnet. Back then, what came to mind as a garnet was a dark red gem. Years later when I started collecting gemstones and learning more about them, I found out about the wonderfully green variety that was called "tsavorite". Tsavorite garnets put most of the emeralds I had seen to shame. They were such a wonderful sparkling green! So being biased to Christmas colors by virtue of my birth, how could I not fall in love with a gem that was outstanding in those shades? As I furthered my gemstone studies with the GIA Colored Stones course, I learned that garnets came in other shades ranging from a purple red to orange to yellow to green and some were even colorless.
Then I started faceting and discovered that garnets proved to be cooperative in developing a nice polish. Plus many of the reddish types in modest sizes were quite affordable for a beginner faceter's budget. Occasionally a flaw or "feature" of the crystal would become a problem by ending up where it would cause mischief. More often, I could see included crystals and needles when inspecting under magnification while I was polishing the stone, but these inclusions would not be visible to the unaided eye in the finished gem.
There were basically two problems with garnets. The first was that the larger red garnets often were too dark to sparkle. They just sat there looking red. Not awful, but not as exciting as one might hope. The other was a budgetary one. Rough for tsavorite and other types which would sparkle even when large was quite expensive. Thus my accumulation of garnet rough has tended towards smaller sizes in the darker reddish shades and fewer, even smaller pieces of the lighter colors.
A few months ago a parcel of Mahenge garnet rough followed me home. These garnets tend to be nicely shaped, fairly clean pieces that run from a light peach to a nice medium raspberry shade. When cut and polished, these stones are wonderfully bright. Most of the parcel is smaller sizes -- .5 to 1 carat finished. This launched me into an effort to work through a lot of the smaller garnet rough I still had from many years ago as well as working on the Mahenge parcel. Once the small rough is properly dopped the process of cutting it is usually low stress. The smaller the facets, the quicker it is to cut and polish them. (The flip side of that is a slight loss of attention can yield a significant error given the scale of things.) The bottom line is that the majority of the stones I have cut recently have been garnets. And lots more to come.
Years ago I purchased a parcel of green beryl which included a couple of very long and narrow crystals. Short of using the trim saw to turn these into multiple pieces with more typical proportions, there wasn't much else that could be done with these other than cutting them into elongated emerald cut shapes. Of course, that results in a boring stone. The solution to that problem was the addition of concave facets which created much more interesting optics and a gem that has gotten a lot of positive comments. (Figure 1.)
Figure 1. Green Beryl
So why not try the approach on some slightly larger stones? The original green beryl was under 5 mm. wide. I wanted to see the result in a stone that was in the range of 8 to 10 mm. wide. In searching through the rough I had on hand, I found a few pieces that met the desired width, but would end up with the length more like two times the width rather than the four times of the green beryl. At least for the initial experiments, that would have to do.
The idea was to test some variations on a theme. Take a basic long emerald cut and add concave facets to the pavilion only. The crown would be a standard step cut so the only thing being considered was the impact of the concave facets on the pavilion.
Figure 2. Rose Quartz
The first piece was a scrap of rose quartz that many years ago had been trimmed off a much larger chunk. It had been ignored as useless for a long time and I was surprised to find how well it suited the situation. For this one there would be three concave facets on one side of the pavilion -- center and close to each end -- and two on the other side aligned between the facets on the other side. The concave facets were created so that they closely approached the keel without actually touching it. The width of the facets was about the same as the space between them. The goal / expectation were for the actual facets reflected in other side of the pavilion. (Figure 2.)
Figure 3. Amethyst
For the second stone a piece of amethyst was selected. This one was done similarly to the rose quartz, except that in this case there were three concave facets on each side of the pavilion arranged opposite each other. (Figure 3.)
Figure 4. Citrine
Of course, for the third stone in the series, yet another piece of quartz was needed. In this case, it was a citrine. For the final stone, each side of the pavilion had five concave facets that touched each other. (Figure 4.)
I expected that one of the combinations above would clearly be better than the others. But so far, I have not been able to pick a favorite. Meanwhile, I have acquired a few pieces of rough which have a length to width ratio of 3. So some rainy day, I will get around to the next step in this series. Stay tuned.
I wish I had taken a photo of the rough piece of citrine from which this gem was cut. When I purchased the rough, I was looking for material that I could use for concave faceting. It was during of one of my false re-starts for faceting and I don't remember if I thought I would saw the rough into multiple pieces or use it for a single stone. When the time finally came last fall that I took it out of the drawer for faceting, I ended up preforming it to be a single rectangular cushion stone. Other than knowing that I would use the OMF machine to put concave facets on the pavilion, I had no idea how I would cut it. It got dopped along with ten or so other stones. They got cut. This one sat there being big and intimidating. Another ten or so stones were dopped and cut and the big citrine still had not touched the faceting laps. It was now the new year and I decided that I could no longer allow that stone to intimidate me.
The first step was to find the outline and the pavilion keel. I started roughing in the shape with the lap I typically use for such purposes and after a bit realized it needed a coarser lap. Once I got the outline figured out it was time to think about the details with respect to facet placement including the concave ones. The initial pavilion facet pattern was a basic step cut. Typically, that makes for a pretty boring gem. However, concave facets placed in the pavilion usually light up the stone and make it more visually interesting.
I decided on three concaves on each side of the pavilion with a bit of space between them. They were placed such that they centered on the middle step extending towards the keel and the girdle, but not touching either. Often the keel on quartz is easy to chip, so keeping the curves away from that area means that should chips appear in the future as a result of handling, the repair required would be minimal.
Then it was time for the crown. Again, the first step was to level the girdle and rough in the shape. After a good night's sleep, I decided that the crown would consist of flat facets only. Rather than using a routine step crown with a large table, additional rows of facets were used so that they and the table were about the same width. When the stone was removed from the dop, the results were as desired. The long facets on the crown made it seem like there were multiple sets of concave facets on the pavilion.