Cut diagrams

I am looking for a cut diagram or diagrams for OEC Beryl.

I have seen a few in rotation on the front page. I thought we had a library of them or access to some.

Help appreciated.

There’s a link to a facet diagram site on this POST
Over 5000 I think, the few I’ve tried worked out ok.
Happy hunting :grinning:

1 Like

Thank you !

Not what you asked, but, being a cutter who cuts for jewelry, cut diagrams are a specialty of mine. I’ve been analyzing cuts on GemCad and its GemRay optimizer for maybe 15 years, looking for the best cuts with the best optical performance primarily, but the also the best weight retention. If by OEC you mean the original emerald cut, it has classic lines and tradition going for it and it produces about the best yield from a long thin crystal like tourmaline or emerald, which can usually be cut with the long axis of the cut along the long axis (C-axis) of the crystal. The drawback to the emerald cut is that face up it has bad light return. Absolutely face on as you examine a ring, it is about 50% or less lit up. If it is tilted side to side, things only get worse. It does all light up if you view it from over 5 degrees above or below, so maybe for some pendants it looks good face on, but with a 5 degree elevation. I’ve been working on this analysis because I have a lot of tourmaline to cut that requires something like an emerald cut and I may soon have some emeralds to cut, too. So far I haven’t found a combination of pavilion angles for the emerald cut which is far enough apart to be seen as separate “glints” (that’s about 5 degrees and IDK whether smaller will work at all) and still have them all light up when the stone is face up. If you get technical, stones are appraised by face up brightness, so a stone that is only 70% lit up loses 1/2 a grade…55% or less loses a whole grade. So far, I have developed a cut from on line instructions that has 80% of the yield of an emerald cut of the same L/W ratio and depth. It has a lot better brilliance…I have a few more comparisons to make to improve it more and I have to compare the pixel cut to the emerald cut for yield, too. I think the OEC may retain its rank as the heaviest stone that can be cut from certain dimensions, but I think because of the better light performance of the other cuts, their value will be greater in many cases. You have to realize that the alternates “face up” at the same size…they look as big…they are just a little lighter, maybe 4 cts instead of 5 cts. Stay tuned. As far as the OEC, there are diagrams for it on line and it is easy enough for a cutter to wing it without a diagram. The angles are the key to light performance, however, and you’ve got to optimize depending on what species you are cutting. Yes, I know that some diagrams have notations that say "cuts with good performance with these angles for RIs from 1.54 to 2.15, but it isn’t BEST performance for any of them. Each species that is more than a couple of tenths different in RI requires different angles. Sorry for the rant, but you actually picked a subject I know quite a bit about. If you find I’m wrong somewhere, please let me know, I’m anxious to improve my knowledge. -royjohn



Excellent information! I haven’t started faceting, yet. But I would very much like to ping you now and again, when I bring my faceting machine on-line. (It supposed to arrive towards end of year)

Mr. Strickland, the author of the GemCad software has retired as of January this year. He is now offering the software for free while the website remains active.

I wasn’t aware of that at the time when I purchased another software suite called Gem Cut Studio earlier this year.

All of the diagrams listed at the resources posted by @PL01 are transportable into Gem Cut as well as GemCad. Only difference I see so far, GemCut has integrated the optimization routine without second software application.

I have been familiarizing myself with both programs, and would like to compare the optimization outputs from each one.

It would be great if you could take a short look at the Gem Cut Studio. Would really like the feedback from someone who has experience with GemCad.

I know you are very busy, so any pointers would be greatly appreciated.



Hi Troy,
When you start to facet, we should talk…you should probably join the USFG and look at their FB page, because some new faceters and veterans post their recently cut stones there as well as their queries about various things. I also get a lot out of researching on the gemology on line forum, where some of the big names in faceting have hung out in the past and given their opinions on various laps for cutting and polishing, Gem ID and all things related to faceting. I knew about Strickland retiring and it is on my list of things to do to learn Gem Cut Studio, but I haven’t yet. I also want to load Tom Herbst’s BOG (a better optimizer for GemRay) on my computer. I had it at one time, but don’t have it on my present laptop. I think it has some info that neither GC or GCS show you directly. While it is available free, it requires some skill to get it loaded and it is beyond me to do it, I’ll have to get my computer guy to help me with it.
So, regretfully I can’t compare GC and GCS for you. My recollection is that one is good for some things and the other is better for others. The young kids who are using GCS seem to think that overall it is better than GC. I’ll see if I can get the guy that told me about the differences to remind me of them again in a few days. I have too many plates in the air at the moment and I’m just not fast at anything. My friend in Kenya at the mines near Tsavo (no, not for tsavorite, unfortunately, but tourmaline) wants to know TONIGHT whether this gas powered pneumatic drill he’s looking at is worth the price. Most of the hard rock mining is done with a long cold chisel bar and a 4 pound sledge, pounding over and over, but he thinks that he can loan this rig out to miners and they will give him a share. Once you see a video of someone pounding over and over to go two inches, you can see how the drill might make someone cut you in for 30-50%! DM me here and we can get in touch by video call eventually if that seems like a good idea to both of us. -royjohn

Thanks Troy. Ill have to see if i can download.

Best Regards,


Hi Roy.
Your right. That was not what i was asking for. Buuuut…i love it when you .make time time to write back.

I did not mean to abbreviate . I actually meant to.write out the words. I do not know how i did not accomplish that task prabably because i was having one of the most upsetting, difficult weeks in watch Restorations i have ever had on 8 yrs. . Late sarurday i finally achieved victory on not 1 , not 2 but 3 vintage watches . Tudor , lady elgin with cal 911,that should of been the first red flag and very , very stubborn omega seamaster , cal 550.Brought to me by the devil himself.

Durfing this powèr struggle, Jason Brim up in Georgia was looking for a OEC diagram for Beryl.

THIS OEC BEING abbreviated for
old european cut .
But PL01 sent over a link. Again. Thank you.

Jason ebded up finding an OEC diagram for rounds.

I had actually sent him my copy of European mux cut not paying attention. , he went 2 days thinking I had sent what he was digging for.

Here are both. … incase.


Hi Troy,
Well, the peril of acronyms! I thought you were talking about the original emerald cut (OEC), esp. when you said beryl, because I was thinking of emerald, where yield is so important, or maybe double blue aqua. I had a nice juicy piece of emerald rough that I was looking at on line that day, so that was also in my mine…having to possibly actually break down and break my rules and cut an emerald cut instead of something that performed better. And, as I said, you actually hit a topic that’s been top of mind for me lately, one I’ve thought a lot about.

I had to take a look at that Mixed European Cut and I can tell you that Robt. Strickland translated that into GemCad as a favor to someone, because you can tell at a glance that it is going to be a pretty bad performer as far as light return goes, with three step separated by 5 degrees on the pavilion…I know that, and Robt. has been using that program long before I ever thought of using it. I’ve seen him put up designs during a talk, and even when he’s going slow for the peanut gallery, I have trouble keeping up! But yes, it is about 60% light return at one angle (not head on) and below that elsewhere, but the worst part is that the light return is in a dumbell pattern so that in the middle of the long side, from the edge to about 1/3 of the way in, it’s dead at almost any angle. A lot of the Vargas step cuts are like this. There was no computer design then, and it seems like they looked at the pattern of facets more than the al-over light return. Rounds, trilliants, some ovals, pentagons from the Vargas books can look decent, but other shapes that are harder to design can be really poor.

I didn’t know you repaired watches! Interesting. I had the pleasure of meeting Jason Brim in person at the recent NC, USFG Symposium. Good guy. We’d only talked on FB before that.

The rest of the list is seemingly mum about my opinions on the emerald cut, so nobody knows or somebody who knows ain’t sayin’…


I’m not sure exactly what that means or if it’s meant for me, but if it is, I can only say (well, yeah, OK, only doesn’t go with say when I write now, does it?) at least it isn’t :imp: :imp: :imp: :imp: :imp: :imp:. And :heart_eyes: :heart_eyes: :heart_eyes: :heart_eyes: :heart_eyes: :heart_eyes: right back atcha!