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Technical guidelines for OEC vs. EC vs. transitional?

Circe

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As more and more of us get interested in old stones, I figured it might be nice to consolidate some of the old threads on the topic, and to organize some of the collective wisdom on the topic. What do we mean when we say "checkerboard" vs. "snowflake" vs. "flower patterned?" While we all know buying fancies on the numbers is a fool's game, once we fall in love with certain stones, can we use the numbers to best define them?

On the latter count, I found the discussion of LGF facets in this thread fascinating: https://www.pricescope.com/community/threads/what-cut-is-this-rb-or-transitional.106881/; in it, Karl posted some really illustrative images of how different LGF percentages could affect the look of the stone (table copied and pasted below). Or, this table, posted by DenverAppraiser and a couple of other folk to give some basic predictive guidelines on how old cuts might be expected to behave:

How 'bout y'all - any particularly informative tidbits you'd care to share?

1Chart5revised1-09.jpg

smalltablelgfchart.jpg
 

LGK

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Well, personally I think that stones with short LGFs- which is what both TCs and OECs usually have- look more quilty or checkerboardy, when they have big tables, and low crowns. That's what you get more with TCs. And they look more snowflakey when they've got small tables, a la OECs. Not technical terms though, for sure! It's just what the patterns look like to me, as a layperson, y'know? :tongue: I wish we still had pics of Surfgirl's ring- that was a pretty classic TC checkerboard type pattern IMO. The OECs sometimes even get the Kozibe effect with the culet mirroring around, when you look straight down on it, if the table is small enough. Once the LGFs started getting longer, that's what I'd consider an early round brilliant, not a TC, really.

TCs tend towards better symmetry too, so that also creates the more regular patterning that looks checkerboardy, I think.

I think Al Gilbertson- who's the real expert on the subject- doesn't use the term transitional cut at all, if I remember right. (I think he uses "European Cut" instead? But I am kind of foggy on the details there, I can never get them straight in my head...) So it's not a "real" category anyway. But it's what we PSers call stones that have a mix of characteristics of OECs, but start tending towards round brilliants, cut after they discovered how to saw rough in half and thus get two diamonds, where before (with OECs) they'd just have to grind off all the excess and make one larger stone. That invention lead directly to the super big tables and very low crowns characteristic of the TCs, since they were trying to squeeze every last point out of the two stones.

The TCs often are heavy on the white light return. They can be very, very bright, like little flashlights. However the trade off is less fire. They tend to photograph very well, due to the white light return and the attractive patterning a lot of them have due to the better symmetry. Personally, in person, I don't care for the lack of fire, however. But, they do photograph especially beautifully. Especially if you take the pics under a tree on a sunny day- that sort of photograph will show gorgeous pastels on the facets. (Surfgirl's photos showed that effect wonderfully, for example.)

You can find stones that have mixes of all sorts of those characteristics. I own an OEC, a later cut one, that if it had a smaller culet, I'd call a TC. It has a high crown, but has 60% depth and a 60% table, and a large culet and x-thin girdle. It's very, very fiery. I think that one is the best of both worlds, you get the fire of an OEC but the symmetry of a TC.

Oh, and I'll also mention- OECs aren't necessarily deep, which I see repeated here sometimes. Some are ridiculously shallow. Their depth was pretty much allll over the map. The shallower ones tend towards laziness under the center facets- not darkness, but a lack of fire from the facets under the table. If you compare such a stone right next to one with more depth, you can see the effect quite clearly- almost all the fire comes from the outer facets. (My mom recently bought an OEC like that- on my recommendation- because she loved the setting, the price was right, and it was sparkly *enough*- and the especially large face up size didn't hurt either :tongue: .) The ones that are overly deep sometimes show darkness under the table. Both are things I personally avoid, but if the price is right, plenty of them are hardly ugly diamonds, just not top notch cut examples of OECs.

The computer I'm using doesn't have many good pics saved- hopefully someone with more patience than I have can dig out some good examples!

ETA: Buying especially OECs by the numbers is sometimes helpful if you're weeding through a large database like OWD's. I usually look at any that have 60%-63% depth, with my preference being 60%-62%, really, and tables up to 60%. And a high crown. The high crown can make the slightly larger tables acceptable, in some instances, if you are looking for a fiery stone at least. I also look at the patterning- I like being able to see the fat "arrowheads" in a snowflake type pattern. I don't mind some random faceting under the table- personally, I prefer it- as if it is too perfectly faceted, it looks too modern to my eye.
 

Circe

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LGK|1317087546|3026468 said:
Well, personally I think that stones with short LGFs- which is what both TCs and OECs usually have- look more quilty or checkerboardy, when they have big tables, and low crowns. That's what you get more with TCs. And they look more snowflakey when they've got small tables, a la OECs. Not technical terms though, for sure! It's just what the patterns look like to me, as a layperson, y'know? :tongue: I wish we still had pics of Surfgirl's ring- that was a pretty classic TC checkerboard type pattern IMO. The OECs sometimes even get the Kozibe effect with the culet mirroring around, when you look straight down on it, if the table is small enough. Once the LGFs started getting longer, that's what I'd consider an early round brilliant, not a TC, really.
LGK, fascinating all around! This first bit in particular caught my eye: my immediate interest is spurred, unsurprisingly, by my recent purchase; I took it to get it appraised, and some of the results surprised me! To my eye, it looks very different from what I'd expect a modern round brilliant to look like, but my lower half length is 76.5%, apparently! The other characteristics fall into OECish territory, though - while I wait for the camera to charge, what do you think of the numbers?

Total Depth: 59.8%
Table: 53.6%
Crown Height: 17.1%
Crown Angle: 36.4%
Pavilion Depth: 41%
Pavilion Angle: 39.4
Star Length: 40.9%
Lower Half Length: 76.5%
Culet: Medium
Girdle: VTK to STN, Bruted

The whole thing makes me want to get a copy of that program Karl always posted pics from, to try to predict how long your LGF can get in relation to how small the table has to be to still have that "chunky" look that makes me think old cut ....
 

LGK

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Circe|1317090736|3026516 said:
LGK|1317087546|3026468 said:
Well, personally I think that stones with short LGFs- which is what both TCs and OECs usually have- look more quilty or checkerboardy, when they have big tables, and low crowns. That's what you get more with TCs. And they look more snowflakey when they've got small tables, a la OECs. Not technical terms though, for sure! It's just what the patterns look like to me, as a layperson, y'know? :tongue: I wish we still had pics of Surfgirl's ring- that was a pretty classic TC checkerboard type pattern IMO. The OECs sometimes even get the Kozibe effect with the culet mirroring around, when you look straight down on it, if the table is small enough. Once the LGFs started getting longer, that's what I'd consider an early round brilliant, not a TC, really.
LGK, fascinating all around! This first bit in particular caught my eye: my immediate interest is spurred, unsurprisingly, by my recent purchase; I took it to get it appraised, and some of the results surprised me! To my eye, it looks very different from what I'd expect a modern round brilliant to look like, but my lower half length is 76.5%, apparently! The other characteristics fall into OECish territory, though - while I wait for the camera to charge, what do you think of the numbers?

Total Depth: 59.8%
Table: 53.6%
Crown Height: 17.1%
Crown Angle: 36.4%
Pavilion Depth: 41%
Pavilion Angle: 39.4
Star Length: 40.9%
Lower Half Length: 76.5%
Culet: Medium
Girdle: VTK to STN, Bruted

The whole thing makes me want to get a copy of that program Karl always posted pics from, to try to predict how long your LGF can get in relation to how small the table has to be to still have that "chunky" look that makes me think old cut ....
Oh, that's interesting! Yeah, I'd probably consider it a later cut OEC or tranny. Does it look chunky, even with the more modern LGF length? It sounds like it's kind of a mish-mash of characteristics that isn't easy to categorize, like my 1.22 ct OEC. You might consider getting the girdle polished by Ari- it might make it a better performer, stones with wider bruted girdles like this one can be improved sometimes, with a girdle polishing. Fascinating, for sure. It sounds like it's lovely, and should have a great face up size. The nice high crown and small table should make it nice and fiery, I would think. I also think this is why a lot of OECs or transitionals don't get sent to GIA- it'd probably get slapped with a RB designation, and thus have a not-great-looking-on-paper cut grade.
 

Circe

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LGK|1317091296|3026525 said:
Oh, that's interesting! Yeah, I'd probably consider it a later cut OEC or tranny. Does it look chunky, even with the more modern LGF length? It sounds like it's kind of a mish-mash of characteristics that isn't easy to categorize, like my 1.22 ct OEC. You might consider getting the girdle polished by Ari- it might make it a better performer, stones with wider bruted girdles like this one can be improved sometimes, with a girdle polishing. Fascinating, for sure. It sounds like it's lovely, and should have a great face up size. The nice high crown and small table should make it nice and fiery, I would think. I also think this is why a lot of OECs or transitionals don't get sent to GIA- it'd probably get slapped with a RB designation, and thus have a not-great-looking-on-paper cut grade.
Yeah, it does! Not as chunky as some - def. not a checkerboard pattern - but distinctly flower-like. Do you have pics of your OEC? I'd love to see some of these oddball cuts that get good results. To me, this is SO much more interesting than the hairsbreadth difference between one super-ideal and the next, somehow - I guess it's the variation! Probably the first time I've been interested in numbers in ... ever.

As for recutting ... I am going back and forth! That was my original plan, but Dave Wolf, the appraiser I saw today, argued the position that I usually take - that old stones like this are like little time capsules, and there's no reason to go messing with them. I figure I'll mull it over while I'm submitting all the paperwork to insurance. Since I'm pretty sure I'll be changing the setting sooner or later (I am in the surprising position of having my usually unconcerned husband expressing a preference - he thinks it looks too much like my e-ring!), I'll definitely have the opportunity ....
 

LGK

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Y'know, I actually don't have any good pics of it, in it's current setting. I have some really *lousy* pics in the thread where it was in a temp setting, but they're utterly covered in dust and fingerprints, so you can't see the faceting very well. Hmmm, maybe I'll try to take a few tomorrow in the day, for you.

I hear you on having a tough time deciding on repolishing a vintage stone. I could have my larger OEC improved quite a bit in clarity- possibly even to IF- and the scratch taken out for sure. But, the flaws aren't eye visible so I left it be. Maybe do what I did- wear it as-is for a few months and then decide. I decided I didn't care enough to risk it on a cutting wheel.
 

Circe

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Gr, argh - I had a whole long post written up last night, just before my computer crashed. Lessee if I can recreate if from memory ....

Reading back over all the posts people have made about transitionals over the years, I'm detecting two distinct breeds: the transitional cut that marries the belly of the OEC to the crown of the MRB (short LGFs, flattish crown, big table, resulting in a chunky quilted pattern and lots of white light), and vice versa, the belly of the MRB and the crown of the OEC (longer LGFs, even if they're not usually in the 80% range like they are today, but with a steep crown angle, a small table, and a look that's sort of like an FIC (also, heh, just thought to run mine, and, yep, the prediction was totally true: it turned out to be a 1.4, FIC), but with bigger facets). What I'm really curious about is which came first, the chicken or the egg - the simple history of cutting as I've read it implies that cutters learned to saw stones, boom! big table, and the rest caught up slowly, but if the second kind were concurrent, which they sort of appear to be, it implies that ... cutters who used the traditional methods were already playing around with the pavilion? Hm.

Al Gilbertson had an interesting post in a thread EmeraldLover1 posted in the thread about her ABSOLUTELY GORGEOUS heirloom ring (https://www.pricescope.com/communit...or-transitional-cut-please-educate-me.113733/)(EL1, if you're reading this, I would love to hear more about it!):

"It’s no secret that I don’t like the name transitional—but from the side-view shot, it looks like the girdle is not knife-edged. I would be suspicious. When I have seen girdles that look typical for today, with a pavilion like the older style, it means that someone has repaired the diamond--probably because the girdle was damaged since it was so thin. They then also touch up the whole crown—often to remove small nicks since the diamond has been around for a while. This means that the table size, etc is more in keeping with modern stones. That table size became more popular with that older pavilion bottom in the 30’s—so it hard to say—but if the girdle is pristine, it has probably been touched up. If, instead, the girdle is knife-edged or near knife-edged, it is a diamond that would have been called “scientific cut” in the 1910’s and 20’s and also “ideal cut” in the 20’s through the ‘40’s. It was not until the late ’30 or the mid-40’s that the lower halves were lengthened and the girdle thickened to what we consider normal today (although a few cut like that this earlier)."

Fascinating! So, judging from Al Gilbertson's take, I know have an ancestral "ideal cut." Fascinating! I need to find me a cutters timeline, or the biography of a diamantaire, or something ....

P.S. - It is grim and grey and gross out here, so the only decent pic I've been able to take is under black light. Come out, sunshine! Lemme get some natural fluor shots!

Glowing .....jpg
 

coati

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Circe|1317225587|3027865 said:
Fascinating! So, judging from Al Gilbertson's take, I know have an ancestral "ideal cut." Fascinating! I need to find me a cutters timeline, or the biography of a diamantaire, or something ....
Ask and ye shall receive. Speaking of ancestral ideal cuts...

Circe, if you haven't already, check out Al Gilbertson's book, American Cut-an extensive history of the round brilliant's evolution with loads of examples and diagrams of old cuts. Gilbertson provides corresponding numbers with the diagrams-very helpful. I think you'd like the book.

Talk about term subjectivity-transitional, oec, omc, aren't always accurate, but they work for basic purposes on PS. We can try to define based on numbers, but there is so much variety among these cuts. Proportions and relative angles truly do run the gamut. In his book, Gilbertson notes the "Leviticus' Brilliant Cut," "Wade's American Cut," the "Amsterdam" "Antwerp," and "London" cuts-to name a few. Scads of cuts, and all with different proportions and angle combos. Additionally, some OECs may actually be old American cuts. There were more diamonds cut in Europe at the turn of the century, but cutting technology was definitely in play in the US at that time.

From American Cut:
"The Jewelers' Weekly reported in 1882 that the perception was that the 'work of cutting and polishing diamonds was often done carelessly in Europe and that American workmen could better satisfy the critical taste of American buyers...' The article credited the a rising demand for American cut diamonds. 'So marked was the difference between the imported diamonds and those cut and polished here, that a demand for stones of American finish was created.'"

Gilbertson's book helped me loosely date my 2.94, (pic attached in old mounting) and I used it as a reference when I worked in old cuts. -A wealth of information!

IMG_01191.jpg
 
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