Jumbo Jack I in the rough	The crown for JJ I ready for prepolish

This design shares a pedigree with many others that originated with mistakes or ideas which produced results that were other than expected. My first stone was a 10mm or so standard round brilliant design cut from amethyst. While I was still working on that stone I acquired some clear quartz points from the Crystal Heaven mine in Mt. Ida, Arkansas during the '96 Tucson Fall Show. Compared to the other rough I had, these points harbored big stones and I found one of them irresistible.

I had already accumulated several books with various faceting designs, but all of the designs with sufficient facets to be suitable for a larger stone were too advanced for a beginner. I figured that it would be possible to add facets to a standard round brilliant by simply increasing the design symmetry from 8-fold to 12-fold and cut something with which I was already basically familiar. While this approach has some merit, I failed to comprehend that when the symmetry is increased, the facet angles have to be changed as well in order to preserve the overall appearance of the original lower order symmetry design.

Standard Brilliant 8-fold Pavilion	Jumbo Jack I 12-fold Pavilion
Breaks @43°, Mains @41°	Breaks @43°, Mains @41°

I should have realized something was amiss when I cut the pavilion of Jumbo Jack I. Using a main angle of 41 degrees and break angle of 43 degrees, the break facets did not extend as far towards the culet as they did on the 8-sided round brilliant I had previously cut at these angles. On the 8-fold design these angles produced break facets that extended about three fifths the distance from the girdle to the culet. On the 12-fold design with these same angles the breaks were shorter and ran about two fifths the same relative distance.

Not what I expected, but it looked okay and somehow the ramifications of this phenomena for the crown side escaped me. The angles were "right" so I figured the stone was "right" and I dutifully proceeded to finish the pavilion and cut the breaks and mains on the crown using the same angles I had used on the 8-sided stone. D'oh...

A faceting lesson in stone. The geometry of what I had cut on the crown was "short" just as the break facets were short on the pavilion. By the time I realized what had happened and understood the geometry it was too late. The only way to preserve the basic appearance of a standard round brilliant would have been to change and reduce some or all of the crown angles from 32, 28 and 13 degrees for the breaks, mains and stars to substantially extend them to meet with an approximately 50% table.

These instructor-given angles worked well on my first stone light-wise and I wasn't too keen on the idea of changing them due to concerns over making them too shallow. The whole idea had been to preserve the first stone's optical characteristics by retaining these angles to minimize the tinkering. Fortunately I was lucky and this new "design" worked out with an aesthetic crown. The table is surrounded by twelve five-sided "petals" replacing the triangular star facets of the conventional round brilliant design. The Jumbo Jack geometry places a greater percentage of the crown's surface at 13 degrees in the petals than a round brilliant does in the stars, but that doesn't seem to hurt it looks-wise in the least.

Jumbo Jack I is about 22 mm and it is a bright and scintillating stone which I'm proud to show off. It has a nice "presence" which exceeds the simplicity of the design and faceting skills required to cut it. The owners of Crystal Heaven were especially appreciative of it when they saw it during Tucson '97 and wanted a stone of their own cut from their crystal. I found a suitable piece of rough in one of their $2.50/pound boxes of points which contained a water clear area large enough to yield a 28-30mm stone, barring any major cutting mistakes or disasters.

Jumbo Jack II was designed as the cut for Crystal Heaven. It preserves the crown of its predecessor, but due to the larger size I wanted to fancy up the pavilion a bit to increase the number of facets and scintillation. The number of pavilion main facets has been doubled by splitting them vertically, and the pavilion break facets have been extended towards the culet so that their tips extend into the view through the table, forming a starburst design. Shown at right is the dopped stone for Crystal Heaven's Jumbo Jack II.

There's already hours of preparatory "work" invested in the stone at this stage, spent high-grading and selecting the crystal, trimming the rough from the point, carefully inspecting it for flaws with Refractol, and properly dopping it. Prior to cutting this design I decided to take up GemCad and worked out Jumbo Jack II with it to help eliminate the "D'ohs" during cutting. It took me a couple of days of learning GemCad and some of its antiquarian quirks to use it to generate the Jumbo Jack II drawings and verify the design, but I feel it was well worth the time. By using GemCad I'm confident the design will also cut in quartz the way it does in my head, and the computer generated index lists are less prone to mistakes than hand compiled ones (one "cutting" error I've already committed).

If you're a newbie faceter and you're thinking about cutting this design, here's a few tips and remarks so you can't say I didn't tell you so...

If you're using a club machine in a class you might do best to steer clear of this design until you have a machine you can use at home. I started Jumbo Jack II sometime in February '97 and did not finish it until early in August '97. It was started on an Imperial faceting machine in my OPLC faceting class which I attended faithfully once a week for 3 hours per evening. If I had not acquired my own machine, I might well still be working on JJ II in class!

When I first roughed out the stone it was about 27-28mm in diameter. That's a good sized stone and it just takes more time to cut and polish large stones. This one also has 121 facets and while there's certainly designs with more, that's also a fair number of facets. My first pass on the pavilion progressed rapidly. I had invested in a 50-60 grit Dyna Disc for roughing in this project and had roughed in the pavilion breaks and then the girdle in just a couple of classes. Things went pretty well (or so I thought) until I got to pre-polish and began to cut the split mains into the pavilion breaks. Even though I very carefully cut in the meets at the girdle, the inner meets on the tips of the breaks and the culet center point were all over the place!

This is because the higher, 12-sided symmetry of this design combined with the deep breaks makes for low angular differences between adjacent facets on the pavilion. These low angular differences tend to magnify and exaggerate cutting errors. Critical inspection of the girdle revealed that not all of the facets were of equal length and it became evident that better technique and more care were required at the girdle going in. I recut the girdle and pavilion on JJ II four times before I was satisfied with the results. After the third pass I transferred the stone to a Graves dop and took it home to work on with my recently acquired Mark IV. I had to wait about 3 weeks for my order of the 96 index needed to cut JJ II, so in the meanwhile I warmed up by cutting a pair of 12 mm round brilliants from tourmalike.

The tourmalike twins were good for practice and getting acquainted with the Mark IV. When the 96 index arrived I recut JJ II for the final time, starting over from scratch once again with what was basically a nice preform after transferring it from the Imperial to my Graves. I still had to do more cheating to bring in the pavilion meet points than I would have liked, but I did finally manage to reduce the geometrical error to the point that virtually all of the cheating was limited to the polishing stage. I ended up with a .95", or just over 24 mm diameter stone. If I don't say so myself, it's a real beauty. I don't think I'd cut this design on anything much smaller - if you do you might want to skip the split mains and just use 12 flat ones. I don't know if there's an upper limit size-wise for this design. It certainly looks like it would wear well on a 50 mm stone or even larger.

I don't have any idea how many total hours I spent working JJ II - I don't run a meter when I'm faceting. But if I were to cut another just like it, I could easily imagine it requiring 40 hours (or more), providing everything went well on the first pass. Your mileage will vary depending on your experience and how obsessive you are. A design goal was to be able to say if you can cut an SRB you can cut a Jumbo Jack II. While that's esentially true, I'm not sure I'd recommend this cut for beginners because of its sensitivity in the pavilion meets to small errors in the girdle outline. However, JJ II was my third stone, and with some perseverance I did manage to cut one I'm proud of.

Desperate for a precise girdle to build on, I tried girdling attachments on both the Imperial in class and at home on my Graves. However, I concluded that it's a lot faster and just as accurate to simply keep the sweeping down and cut by ear - consistently returning during a course of facets to the same place on the lap until the ticking just quits. I have come to appreciate that bigger stones can mean bigger problems but they're good for your soul! The crown is easy money in regard to meets compared to the JJ II pavilion - the petals effectively eliminate one set of meets over a standard brilliant crown, and the crown angles between courses of facets are greater than JJ II pavilion angles by an order of magnitude or more.

So, was cutting this stone worth it? Well, I learned a lot in the process and was quite pleased with the end result myself, but I'll let you be the judge of that. Here's an image of the Mt. Ida quartz specimen I acquired in trade from Crystal Heaven for Jumbo Jack II. This magnificent cluster of crystal is about a foot high and when you lift it you definitely know you have a specimen in your hands! Of all the specimens Crystal Heaven had on display at the '97 Tucson Fall Show, this piece was the best to my taste. It is not a common occurrence for me to be able to point to a dealer's best rock and say "I'll take it!"

I've decided I like working big (at least at quartz prices for the rough). The Jumbo Jack name originated during an Old Pueblo Lapidary Club faceting class when a fellow student observed me trimming the rough from the crystal for number two. While she was referring to the size of the stone, the name is also descriptive of the size my head has gotten from the oohs and aahs Jumbo Jack I and II evoke when shown off. Following Jumbo Jack II, I plan to cut an even larger stone from some clear quartz originating in the Russian Urals... Yumbo Yaksky III?

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Bob Keller