AGA fancy cut standards for radiants, emeralds and princesses

[moosewendy]

I am confused as to the AGA fancy cut standards for radiants, emerald cuts and princesses. It seems to me that the way a radiant reflects light is more similar to a princess than to an emerald cut, yet the AGA lumps radiants and emeralds together while separating out princesses. The princess cut standards appear to be much more lenient with respect to depth, crown height and table. Is there any scientific reason why radiants and emeralds should have the same proportions, but princesses should be different? Is there any research that concludes that its OK for princess cuts to have higher depths, larger tables and flatter crowns than radiants or emeralds, or does this reflect a weakening of princess cut standards to conform to the market of poorly cut stones? It seems to me that, if anything, radiants and princesses should be lumped together, since they are both modified brilliants. It makes sense to separate out emerald cuts, since they are pure step cuts and reflect light so differently.

Can anybody shed some light on this?

 

[oldminer]

It is science that created these charts. It is experience in examining these stones and making an attempt to quantify the experience into parameters. Radiant cuts and emerald cuts share the same rough to create either one. Only the faceting arrangement differs. Princess cuts are without cut corners (nearly all the time) and are what some might refer to as a "high yield stone", one that has a lot of weight for its apparent face-up size appearance. Princess cuts are relatively modern as are Radiant cuts, but they differ in their shaping and light behavior.

That''s why they are not lumped together. If you only want science, it wouldn''t be diamonds.... There is a degree of art, craftmanship and expertise involved beyond physical data.

 

[moosewendy]

Thanks Oldminer, but you didn''t really answer my question. You say that radiants and princesses reflect light differently, so they shouldn''t be lumped together. This makes sense. But radiants and emerald cuts reflect light completely differently, yet you do lump those shapes together. Why the difference. The fact that the two cuts come from similar shaped rough isn''t really an answer. The cutting styles are completely different and there is no obvious reason why the ideal proportions for the two shapes should be the same. Is it just a coincidence that they are the same, or is there something I''m missing? I''m not questioning whether your standards are correct, I''m just trying to understand the logic behind them. The nicest radiants I''ve seen seem to fall into your 2A and 2B category. Very few 1A or 1B''s seem to exist, and those I''ve seen haven''t seemed any nicer (in several cases they were not even nice).

It also seems like your 2A and 2B princess standards cover a large percentage of the princesses out there, while 2A and 2B radiants are quite scarce, and pretty much represent the cream of the available crop. Does this mean that most princesses are decently cut, but most radiants are not? Or is the standard for 2A and 2B higher for radiants than for princesses?

 

[Hest88]

In my mind, it always had to do in part because of the step-cut facets along the crown of the radiant coupled with the more rectangular shape (as opposed to the more square shape of most modern princesses), made the light entering a radiant closer to that of an EC than that of a princess. I could ould be completely off, though.

 

[oldminer]

Emerald cuts and Radiant cuts are the same shape, just with different facets. Princess cuts are a different shape and deserve different consideration. Cutters typically make lumpy, full made, deep diamonds where few standards exist so you see the lack of well cut radiants and emerald cuts. Cutters have not adopted the AGA approach and I can't make them do it. Only consumers can when they object to overly deep stones. Trim off the fat and make a fine cut....

Certain vendors and cutters have recognized the AGA approach with the more popular princess cuts and now you can find a finely cut one, if you diligently search for it. Again, this is consumer driven because cutters prefer to sell weight, not fine make. There are still many consumers who prefer or don't know better who will insist on more weight...There are retailers who haven't a clue about a finely cut princess cut. That's the way it is, but it is changing.

 

[moosewendy]

It makes sense for proportions to change as a stone becomes more rectangular, but the AGA doesn''t apply any distinctions for shape. Also, the crown on a princess is faceted exactly the same as a radiant, so that can''t be the answer.

 

[oldminer]

You do not have cut corners on princess cuts. The crown of a radiant is not the same as a princess cut simply because of this. You rarely see square radiant cuts, but often see square princess cuts. Proportions approaching square or perfectly round are far easier to apply and to appreciate than stones with different length and width. Stones that are enither square or round, always have more light and craftmanship issues.

If you don''t want to use the AGA standards, you can certainly find more diamonds that look nice, but have problems that you might not fully appreciate. That''s certainly an okay way to look at the situation, but I do not think it is the best way.

 

[moosewendy]

Oldminer, I appreciate your replies, but I still don''t understand what you''re saying. You say that radiants and emeralds are the same shape, "only" the faceting is different. Is the facet arrangement irrelevent to an evaluation of proportions? Since, due to its different facet arrangement, the radiant reflects light very differently than an emerald cut, wouldn''t you have to at least consider whether the proportions that worked best with that facet arrangement might be different as well?

Are you also saying that the princess has completely different standards simply because it has sharp corners, thus making it a different shape? If you cut off the corners on a princess, does it suddenly require completely different proportions to maximize its brilliance, since it''s now the same shape as an emerald cut or radiant? Will it suddenly need a lower depth percentage, smaller table and fuller crown? Or does it reflect light exactly the same way as it did before?

 

[Hest88]

Don''t know if this well help, but the top is the princess facet arrangement, middle is radiant, and bottom is EC.

 

[Nicrez]

Sorry, but I smelled a radiant thread and came running...

First let me express my deep and utter dissatisfaction at jewelers who consider a princess with cut corners a "RADIANT".

No. Please... No.

Hi Moosewendy! I noticed you are a radiant fan! Welcome!!

...the more the merrier!!!

Ok, I agree with Old miner that a Radiant and a princess are not the same, as most radiants out there are NOT square... As such those should be treated a bit differently, and as Moosewendy said, they probably should help account for the shape difference with an adjusted light measurement for the depth and table being inconsistent throughout, unlike the round and squares...

As such, would a square radiant then be subject to a princess cut chart? Also, would the out of square princesses (L/W @ 1.05+) be considered under the Emerald Radiant charts?

Also, I have to say, Thanks Old Miner for trying to quantify some sort of standard for generic radiants out there, as many people have generally no clue what make s diamond so brilliant, etc...Radiants have been mimicked by so many people (as princesses have) and the lack of standardization (outside of the Original Radiants) makes these stones very unimpressive alternative to many buyers and too difficult to find in a good cut. SO SAD!

That said, I have honestly never seen a 1A, and I could say that I have seen at least 35+ generic radiants and about 5 Original Radiants, but not ONE was within the AGA cut of 1A. Do they exist? If so, who has seen them (jewelers out there if you can chime in now!) Because I would assume they should or else they would not be considered top notch, unless it was simply a hypothetical measurement that is elusive to all consumers, as they are simply not cut with such proportions...

If I may impose on any jeweler who has one in a 1A cut available to possibly post a picture???

I too would like to undrstand the cut charts. They were helpful in weeding out some uglies at first, but the 1B I saw actually was terrible...so I went with a 2A cut... It made me sad to have to get a stone that wasn''t the BEST rating, but it was the best visually, so I got it...

Also Hest, the Radiant has ONE step in the Crown, and a hybrid of a step and brilliant in the pav. It does share the cut corner with the emerald as well, but I honestly, think it behave unlike a round OR an emerald in both reflection and refraction BASED on the facets, so considering each proper facet angle to the appropriate crown facet for such measurements, this stone should (in my book) have it''s OWN cut chart that accounts for different plays of fire and brilliance in comparison to rounds, princesses and emeralds... no?

When I grow up I want to create the definative radiant how-to guide...but first I will need something to research...Anyone want to donate some stones?

 

[moosewendy]

Oldminer, is your distinction square vs rectangular or radiant and emerald vs princess cut? If it''s square vs rectangular, then should a square radiant or emerald cut then be evaluated like a princess?

I''m still not clear why radiants and emerald cuts should be the same. We''re all obviously free to decide for ourselves whether to use the AGA charts. I''m simply trying to understand your groupings since they do not make intuitive sense. If your experience has taught you that all diamonds with the same shape should be proportioned the same way, regardless of facet arrangement, then I respect your view, but it is certainly not an obvious conclusion, and I suspect that many gemologists would disagree with you.

My initial question was simply whether there existed any scientific data to support your conclusion. It appears that you are not aware of any such data, but that the grouping reflects your subjective conclusion reached as a result of your intuitive sense as informed by your many years of experience. If so, you may well be correct, but more research needs to be done before the information in your charts can be relied upon as fact.

It may be that the industry does not cut to your standards not only because they are trying to swindle stones, but because meeting your standards will not necessarily result in a nicer stone. Perhaps this is why no diamond dealer would ever purchase a fancy shape diamond sight unseen on the basis the information contained in your chart.

 

[Nicrez]

David, or anyone else:

What shape rough Radiants are cut from and if any other shaped stones are derived from that same excat piece of rough? Is it normally possibly to cut more than one stone from a radiant rough? I know it''s slightly off topic, but I am curious...

 

[moosewendy]

Nicrez, radiants are generally cut from crystals. Depending on the layout of the particular crystal, this rough is cut into princesses, radiants, emeralds, cushions, etc. If a crystal is sharp (i.e has sharp corners), and has a square model, it is always cut into a princess because the yield is so high (sometimes as much as 80%). If the corners are rounded or broken, it often makes sense to make a radiant. If the model is rectangular, then the choices are emerald cut or radiant. A rectangular princess will give you much better yield than either an emerald or radiant, but is hard to sell because the proportioning of a princess doesn''t work well on rectangular stones. You can also cut radiants (or cushions) from roundstone rough that is off round. Since rounding off the stone can lose a lot of weight, and a radiant or cushion can be off square without losing value, it often makes sense to cut these shapes rather than rounds.

 

[oldminer]

Depending on the shape, I would suppose a cutter can generally cut either an emerald cut or radiant from the same rough. Cutting a radiant can give a lot of control to the cutter on the apparent color of the diamond that cannot be done with an emerald cut. For this reason you see most fancy color diamonds cut radiant style, but very few cut emerald cut style. The placement of facets and angles in the radiant can make a diamond look darker, or more colorful. I don''t think this can be readily accomplished with a standard emerald cut.

We don''t see many square radiant cuts, but we see lots of square princess cuts. Obviously the princess comes from rough that could cut a round diamond, but the extra weight saved by keeping the 90 degree corners has added value to the rough. Only if there is a "problem" corner would they be cut away.

 

[moosewendy]

Is the yield advantage in a princess due mostly to the sharp corners or due to the proportioning? By retaining a flat crown and deep pavilion, doesn''t the princess retain most of the raw shape of the rough material? To cut a round stone (or a well cut radiant for that matter) from that rough, you would need to build a fuller crown and flatten the pavilion, a process that loses an awful lot of weight.