Thanks John.
Something I forgot to attach to one of my posts about cutting this stone is the advice given with the cutting instructions, which are below.
“Five Star Cut USFG SSC Master Class Design by Robert Strickland Test cut by Homer Barrs
This is an easy, doable design for the Master class in this competition. Most of you have your set of procedures to cut and polish your gems which you have developed over time. Here are my thoughts and how I took on this one.
I found this stone to be a very enjoyable cut, after several attempts. What worked best for me was to do the girdle facets first. Then instead of starting with the pavilion facets, I cut the crown facets first. I cut all of the crown facets with one lap before going on to the next lap. This way I made sure that I could get all of the meets and angles done right. Once I finished with the crown, I proceeded to the pavilion facets. I was able to meet all of the size and meet point requirements this way.”
Cutting the crown first was very good advice because I would have stuffed the stone up doing it in the traditional way. Usually it does not matter if the angles of the facets are not precise, as long as the facets are of equal size around the stone. But with those five stars it matters a lot, because the angle alters the size of each part of the star and they should all be the same. 1200 grit is the finest of my bonded laps and I recut the crown three times to get them looking right.
Hi Frank,
It looks great. The reflections from the surrounding colours give us an appreciation of the complexity of the crown.
Hope you do well.
Are you going to enter the International Faceting Challenge?
Regards
Gordon
That is a nice nice looking gem, Frank. And I, also, hope you do well in the comp. I’m nowhere near this level so it’s nice to see what you comp cutters are able to achieve.
Terry
Thanks for the responses guys.
Yes I will be entering the IFC for the first time Gordon. Not expecting to get anywhere though, but I enjoy the challenge of competition cutting.
Frank.
I guess it is a case of "whatever works best". However I am interested to know what was the norm when the Guild was first formed? What drove the change to cutting the pavilion facets first? Is it a matter of best light return from the pavilion facets or best appearance of the crown facets? Maybe judging rules had a role?
Hi Bruce,
I suspect it was a consequence of the work by Long and Steele on meetpoint faceting. Once you start cutting to a pcp or tcp, cutting the pavillion first allows you to maximise the size of the stone.
Cuttimgthe crown first means that you would need close to twice the height you need to cut the pavillion first, a great deal of the material needed for the TCP would be ground away when the table is cut.
Regardss
The best reason for cutting the pavilion first is to maintain performance - if you run short of material you can drop the crown height without too much loss, but if you drop the pavilion angles you may well have major problems. When cutting natural materials with flaws, you often encounter such problems.
Much to my surprise I won the 2019 US masters competition with this stone and even more to my surprise I scored a perfect 100.
I do have a fairly accurate way of setting the facet angles on my machine and it works ok on most stones. But it didn’t come close to finding the angles for the 5-star facets on this stone. Facets E D and H length and width uniformity depend on them being cut accurately to the specified angles and mine varied slightly. I’m assuming I would lose points due to the facets not being uniform.
So, what made it possible for me to cut them so they all looked the same was the digital vernier I have fitted to my machine.
I wrote an article about it in Facet Talk 228 page 5.
By keeping a record of the height of the faceting head on the mast with those 5-star facets, I could by trial and error get them all looking the same.
This is simply by raising or lowering the head incrementally, thus altering the angle till I got it right. Three attempts at the 1200 grit stage to recut the entire crown.
They recommended cutting the crown first and looking back at it, it’s the only way it can be cut accurately.
Unable to add pictures for some reason.
The picture of the cutting instructions for this stone is attached to my post 26 May. Don't know why it won't let me attach it again.
C O N G R A T U L A T I O N S! Great news Frank.
I look forward to seeing your results in the 2020 comp.
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