The lower girdle facet (lgf) length seems to be the surest thing (70% is still possible among modern stones that already stand out) - star facet length seems to overlap more between old and new brilliants.Is it the low star facet and lower half facet lengths
I too very much like this face up photo. However you are eerily correct about size and color!If you are really seeking "precision", I like the cut Victor Canera offers over the AV . But the bugger there might be finding the color, clarity and size I suspect you would be looking for.
But it is definetly personal preference. I like a large culet, kozibe , high crown, and a flower petal center. I also found that I prefer a little wonkiness rather than perfection. Who knew?
You'll have to see a few to hone in on what speaks to you guys!
Why would you know better?[you are reminding me of the last time I touched DiamCalc, the cut modelling software most talked about around here, ending up with some beautiful possible makes with such short facets & about 40 degree angles for both the crown & the pavilion; today I would likely know better; good fun.]
If you read my original post you will see I point out that a GIA OEC cert is useless for determining the cut or beauty of the diamond. No offense intended, but that's the whole point of this thread!This is a nice academic discussion but I recommend not looking at GIA reports to figure out your preferences. Table size below 50% and high crown over 35% is a good indicator for OEC and OMB and OMC cuts (as well as LGF under 70%, as AV says) but if you like Transitional or Early Modern you will see a larger table and shallower crown angle and higher LGF%. GIA report can tell you roughly what you might see, but you might “academically” like the stone, yet not like it in person.
You’ve got to decide if you want truly authentic untouched antique (these can be excellent to poor. Many nowadays are poor. Rare excellent cuts are usually with dealers), or repolished antique (slight tweaks to the angles and clean girdle. This tends to clean up a chipped stone but ruin the original cut), vs. recently cut antique style (these can be junk, or they can be optically excellent cuts depending on who cut them). If antique vs. modern doesn’t matter, that opens up everything. If it true untouched antique does matter, then you need to go to antique stone specialists and ask for it.
I’d recommend that you look at videos and photos on Instagram until you see the one you like, then go visit it. Or, identify what you like and ask an expert dealer like Adam at OWD or Grace at JbG to look for and find one like that. You could also take a chance and go visit a local dealer who has antique cuts. I’ve seen a lot of very nice antique looking cuts on Parks Fine Group Instagram, FWIW.
In summary, it takes a lot of time to analyze and select an antique cut diamond from just a GIA lab report, and many times the report doesn’t have all the angles anyway. And many times dealers don’t have a report for an antique stone, and sometimes the stone is set so it can’t be analyzed. So I wouldn’t use a GIA Report as a way to look for, screen and identify potential keepers.
yesI may be doing this completely wrong so would appreciate some feedback from the experts.
Karl, thanks for your response. I think I understand everything you are saying except the comment above. Could you please explain this using layman's language so I can better understand the point you are making.For example the steeper the crown the shorter the stars should be to lower the upper girdle facet angle.
They knew this back in the day which is why 45% or even 35% stars were not uncommon.
The upper girdle facets are between the end of the stars and the girdle.Karl, thanks for your response. I think I understand everything you are saying except the comment above. Could you please explain this using layman's language so I can better understand the point you are making.
Maybe yes, maybe no. If we had data showing multiple combinations of crown and pavilion angles with various facet lengths produced beautiful OECs then I would have to agree with you.
We upgraded DW's ER to a 2.01ct MRB on our 25th wedding anniversary back in 2006. We would have to wait until next year for our 40th, but this year will be 40 years since we first started dating, so that's reason enough for an upgrade, don't you think!I guess if you were shopping for a perfectly cut oec , and the knowledge that it was perfectly cut was the thing about the stone that was most appealing to you. I do get what you are saying.
I think what some of us are trying to say is that there is something else in the appeal of these stones. If we are talking about truly antique oecs, they were not cut with modern precision and tools. They were not cut with computer aided guidelines. They were handcrafted, the rough turned in to what the cutter saw as most beautiful. Now some are frankly wonky: offset culets, dead centers, asymetrical as can be. Those are easy to spot. But by seeking only perfection in cut, you might dismiss a gorgeous stone. My stone is far from perfect, but as soon as I saw her with my eyes, I knew she was it. For ME. Someone else might say they prefer a smaller culet, a lower crown, prefer more windmill then flowery facets, a bigger table, a smaller table, etc. That's personal preference!
What's unique about these stones is that they ARE unique, each a little different. In my opinion they really can't and shouldn't be analyzed as to every ratio, degree, percentage the way some do with the modern brilliants. (There maybe you can just decide you don't like the numbers, and move on-- plenty of fish in that sea. )
I had to get some guidance when I was looking, needed some way to weed thru the options. But once I knew the basic parameters needed to find the stones with the look I wanted, I relied on my eyes after that. I wanted a sparkly, firey stone with great movement in the facets , beautiful flashes of chunky color, kozibe and a big culet. I didn't need to know all of her measurements to know she's perfect for me.
That is the point I was trying to make.
Hope that makes sense.
Yes, yes, yes! Wouldn't it be nice to know how they achieved such a beautiful OEC with a total depth of only 57.7%. I am willing to bet this stone had a crown angle less than 40°. In fact I suspect that just about every OEC with a decent spread has a crown angle less than 40°. Quite why GIA made that the minimum angle to qualify as an OEC is a mystery to me. Here's a table I put together of crown height vs crown angle for various table %.@prs I was wondering about short star facets on a recent thread, so I have OEC on my mind still.
eg. proportions - www Numbers like this are unexpected enough to not put in writing. There are so many beautiful versions if the round brilliant, one for each piece of rough, at least.
Karl, thank you so much for the education, I think I now know a lot more about the different facets and their relationships to each other.The upper girdle facets are between the end of the stars and the girdle.
So if the stars are shorter the upper girdles are at a shallower angle because the are longer.
If the table is larger for any given star % the upper girdles are shorter and steeper.
When the upper girdles get to steep in relation to the lowers there are performance and appearance issues.
So for very steep crowns you need small tables and/or short stars or the upper girdles are to steep.
The change in the upper gidle angle is the largest impact the star% has on a diamonds performance with many crown angles.
It changes with the CA angle and lgf%.Could I impose on you again to give me your opinion on what an acceptable range might be for PA, and if the optimum PA might change with steeper CAs?
Where in the lab reports do you pick up on the stars specs?Whilst I read @Karl_K's article on PAs for the third time, I think I have a pretty good handle on the effect star length has on OEC facet "chunkiness".
Here are two photos that show the difference between 30% and 50% stars. The diamond in the first photo has stars that are close to 30%, and the diamond in the second photo has stars that are closer to 50%. What is your favorite flavor?
It's not in the lab reports, that's why we have been flying blind. However there is a way to figure it out for yourself with just a ruler that has a mm scale.Where in the lab reports do you pick up on the stars specs?
Thanks so much! I actually meant measurements in regard to the cut. Depth is 64.9. When they are deeper, they seem to lose diameter. Mine is about 2.3 cts and 8.4mm which isn't bad. The table is 45.4. Crown height is 19.7% which is higher than ideal cut rounds which are usually around 15% give or take a little.
Thanks for the advice @diamondseeker2006. Your August Vintage OECs are fabulous, and yes with AVC or Victor Canera one does get a beautiful stone without all the hassle. Also with both of these brands you get terrific face up size for a given carat weight.I honestly think you are overanalyzing! You just need to start ordering stones to look at in person. I knew I'd have trouble finding an antique OEC that was exactly what I wanted (an outstanding cut, like you are interested in), so I ended up with an AVR which was cut by a master cutter's team. It's the one in my avatar picture. Even AVRs and CERs are different from each other. I ordered about 7 AVRs before I decided on the one I kept. It's a combination of every single spec, and that includes color and clarity, too.
I will tell you that I have a second stone in a lower color that was an OEC which Jonathan had recut bascially to similar specs to my first AVR. So your idea is a good one. I really recommend the specs of mine. It is not so deep as to lose a lot of weight and it has the beautiful floral facet pattern. However, no one is going to cover your diamond in the case of accidental damage in recutting (which is rare and I haven't heard of it happening since I have been here), and that could be costly with a 4-5 ct stone. So you might want to reconsider the idea based on that. I do think you can still find some good deals on OECs that don't have a great cut, but you are really limiting yourself if you are in the 4-5 ct range.
This pic doesn't really do them justice, but here it is just to give you an idea. Top is O color and bottom is I color.