by Art Kavan, Old Pueblo Lapidary Club
Not everyone wants to be or can be a competition cutter, but everyone should give it a try. It will make you a better facetor whether you cut for fun or profit, the benefits or real. You are not really competing with others but yourself and the judge as it is mostly each individual stone against the score sheet.
The most important thing is a thorough understanding of the basics as without the foundation the stone can’t be built to competition level. The next in importance is polish, if you can master polishing you are well on your way.
I will start with a basic discussion on the importance and methods of making sure you have center point when starting the stone. We will use the example on a simple round but most competition stones in the masters level are not, but the principle is the same. I have spent many many hours on this and here is my methods. On a round there are three common ways.
# 1 is to cut all the break facets to a center point. Now right here we have a problem, some will cut with the sound method, most will cut with the needle method and a few will cut with digital or ohm meter method. Makes no difference as after we do the best we possibly can, now we use the eye’s and work all the facets that don’t reach the point in. We now think it is perfect center point.
Maybe? now if you cut your girdle facets and you follow a exact line all the way around and it comes out perfect with out cheating you have a square pavilion, notice that I say square pavilion and not a square stone, you won’t know that until you make the transfer as I will explain later. If you have to cheat at this point whether it is cutting the girdle line or break line, it is telling you that you are not at center point.
#2 If you are short on material and want to save a little you can use a method of cutting the breaks not to a center point but part way with the mains and culet facets closing the stone later, you can get very close by cutting the breaks to a depth or sound and then following a line with the girdle facets I have cut the girdle facets with an ohm meter and then came back with the follow the line cutting the breaks with good results.
#3 You can cut the girdle with any of your depth of cut methods to the best of your ability and make a template out of an aluminum can and cut every one to size, it works OK on larger stones like fifteen MM and above. I spent a lot of time with this method as Ralph Mathewson instructed me on this but I don’t use it much any more. Two very good ways to check for accuracy are use your calipers and measure flat to flat all the way around, they should all be exactly the same measurement. Positive proof is if your breaks meet perfectly when you cut your mains, if not fix it now, other wise you have a nightmare on your hands if you proceed.
If you have completed it very well up to this point the rest is simple and most of the time is easy. I usually rough the stone in with a 360 leaving 1mm and then rough in with a six hundred leaving three to two tenths of a mm then pre polish with a 1200 steel Cyrstalite, all of the above is done with the 1200 after the rough in process. Lets say your stone has to be ten mm, cut it no bigger than 10.1 and then polish the girdle.
Always cut to the closest tolerance here is why, a lot of competitions in America will give you .5mm plus or minus, so that means you can be 10.5 or 9.5 with out penalty. But I lost a competition because two of us had perfect scores and to break the tie they measured the stones again and mine was two tenths over and my competitors was one tenth over, both with in the limits of the rules but still used to separate us.
I try to get to polish as quickly as possible as this is where the competition faceting begins. Depending on the material I prefer the ceramic, that in itself is a whole writing and I have written several articles in the past on the ceramic, I use one hundred thousand Crystalite diamond spray just as it comes out of the bottle for a pre polish and to feel the stone out. I keep very good notes as I am working my way up through the stone, all material has soft and hard spots, I want all surprises to show up now as I will come back with two hundred thousand Italdo diamond for a final polish and tweaking all the meets.
OK we have come this far and we are feeling good about the way things are working, you are approaching the zone that 95 percent of all competition cutting is lost (the Crown). WHY? answer — Transfer! most do not pick up on what happened in the transfer process. I have talked with and visited with most of the top cutters today and like myself have come up with all kinds of ingenious ways to defeat this problem. My solution after two years of fighting the problem worked for me and now it is a pleasure and a relief when I transfer the stone and cut the crown.
I will show a short demo at the OPLC get together on 02-5-02. It is a very simple process of double dopping so you can figure out where your zero on your cheater is actually at before you start cutting. I can’t tell you the agony it caused before getting this as a solution. Here is what always happens, you turn the stone over and follow you girdle line around and it doesn’t meet. So you adjust your cheater and through trial and error you work it out so it is perfect. Congratulations you have just tilted the crown, by that I mean you have an uneven girdle.
Now some will cut at 96 and then cut at 48 and then cheat from both directions and work it out or you can divide into fourths and do the same thing or you can try depth of cut like sound, needle or ohm meter but there will be saw tooth with that method so don’t kid yourself. I have been very successful as a competition facetor as I was fighting my way through this process and I know others have done it the same way. Now if you have worked your way through getting your girdle perfect the night mare has just began because if you started out with a half degree of cheat at the girdle it will turn into a whole degree of cheat by the time you get to the top or more depending on the complexity of the design.
In the end you will never cut a perfect stone because in the area of the star facets there will not be perfect equals, very subtle but detectable to someone who’s been there done that. The point is that after transfer if you have to cheat in the girdle and thus tilting the crown you are going to have problems, not unsurmountable but problems. Now a lot of folks are going to think hey what’s he talking about I never have that problem. If you don’t ( it is possible) you are very lucky but my guess is you don’t see it.
In competition faceting the most important issue is being able to see and know what you are looking for. For instance, on my second stone I realized there was no way possible to cut and polish the table in last and have perfect meets, now the table is the easiest facet on the stone. That goes for meets, there are several ways of detecting proper meets, most important is being able to see a good polish. I have looked at a lot of stones from world class as Wing Evens to folks just starting out and it is amazing what the deference is in what people see.
I have only talked about a very short part of competition faceting, other subjects that might be of interest are sequencing as I know I have cut stones using sequences entirely different from what the designer intended and it is an interesting subject.
Most important as a subject, Polish, Wow will the Egos come out on this one. Listen folks I want to let you all know that I don’t claim to be any final authority and know there is plenty of room for controversy, my views are strictly my own and you can form your own conclusions.