Does a Standardized "Best Cut" exist for Old Cut Diamonds?

[lulu_ma]

I'm riffing off a convo that I started with Garry on the 'Face-Up Color' thread.

I've been studying/shopping old cut diamonds for a few years now. I do not believe that a standardized "best cut" exists for any antique stone shape.

The charm of antique stones for me lies in the wonk. I do look to maximize what I'll call "rainbow fire." I guess brilliance is less of a concern for me?

As the old cut OGs have said before, antique diamonds have to be judged with your eyes. I do take things like depth and table size into consideration, but there's too much variation to say that a certain table size would always pair well with a certain depth percentage. For instance, my 7 ct OEC is outside of the acceptable "very-good to excellent cut" cut grade according to David Atlas' Screening Chart (49% table/ 66.7% depth), but she's pleasing to my eyes.

I think it's impossible to come up with a "best cut" standard unless I wanted an antique-inspired stone like an AVR.

Curious to hear your thoughts @Garry H (Cut Nut).

Here's a picture that exemplifies the cut variation that I am talking about:

 

[maryjane04]

I think there's too much variation to agree on a best cut not to mention our preferences differ. Although a few years ago most PS'ers would favour the flowery oec faceting. Lately though we've embraced the wonk a bit more.

There's also avr/avc or those precision cuts however some of us prefer genuine antique cuts.

 

[Victor Canera]

I think this is a very good question.
Since the labs don't define what an ideal cut OEC diamond is, it's kind of been up to a vendor to fill the gap and interpret what that is. We have our own interpretation while other might have theirs. I think the cut precision is a big part of it. With great cut precision, you're able to achieve a nice symmetric facet pattern. We design our OECs towards a transitional cut which yields that floral facet pattern that our clients really appreciate. The other ideal recipe is the light performance which is really important at the end of the day as well. There's nothing worse than having a stone obstruct heavily and be dark or under-performing. Old vintage diamonds do absolutely have their charm as well and each product has people that appreciate them.

Good luck!

 

[Dreamer_D]

If I was buying a newly cut stone that emulates old style cuts, I would say "yes" and I would want the most precise cut possible.

But that is not where my interest lies. I collect true old cuts. I've owned many over the years and all have had different proportions. All very beautiful to my eyes. I do think there is such a thing as a badly cut old cut. I am not a romantic "they are all beautiful" type. But the mix of proportions that I would group under "well cut" for old cuts is much wider than what I would put in the same category for a modern round.

 

[Karl_K]

Depends on who you ask.
Many old stones are cut with more contrast(dark zones from obstruction) at ring distances than more modern stones.
A lot of them with bling out in a pendant earring or tiara but are overly dark by modern ring standards.
This is even worse when judged in in the too close distance(30 degrees) to nuts close(40 degrees) the AGS system pushes.

It is old cuts that 100% convinced me that make everything a mrb is 100% wrong.
What does that mean:
MRB ranks as:
Brightness - top end.
Contrast and patterns - mid range.
Fire in highly optimal fire lighting - mid to top.
Fire in less than highly optional for fire lighting - poor to fair
Scintillation - There is really not a bad or good here you have large and slow flashing EC on one side and fast and small flashes of a radiant on the other both can be appealing but totally different.
The MRB is in the middle somewhere. Some will call it well balanced.

I for one do not want to see all of the fancies cut to meet the MRB criteria.
Do not turn them into MRBs and make it all about brightness.

 

[Dreamer_D]

Do not turn them into MRBs and make it all about brightness.

I enjoy looking at my old cuts at close range. I like to peer into the stone and see the facet patterning. That cute open culet. I also enjoy the light show in high spot lighting and the colors in indirect/filteted. But brightness? Not such a draw.

 

[oldminer]

For those who appreciate a historical perspective, back is 1999 I created a chart of proportions for OEC diamond cut classifications. Things were far less technical then, and old cuts continue to be popular without 3EX grading problems. These numbers helped me and my dealer customers judge and learn about how to learn and appreciate better cutting. The range is broad enough to be of use in screening for good potential appearance or some degradation of appearance. Much the same parameters fit OM cut diamonds, too. The optical mechanics don't change even if the stone is a bit off round since there is no Ideal standard possibly with the way these are cut. As a dealer, one knows a diamond looks good or doesn't without consulting numbers and parameters. Your own eyes will tell you the same thing if you practice the skill of observing light performance in gems.

 

[Dreamer_D]

For those who appreciate a historical perspective, back is 1999 I created a chart of proportions for OEC diamond cut classifications. Things were far less technical then, and old cuts continue to be popular without 3EX grading problems. These numbers helped me and my dealer customers judge and learn about how to learn and appreciate better cutting. The range is broad enough to be of use in screening for good potential appearance or some degradation of appearance. Much the same parameters fit OM cut diamonds, too. The optical mechanics don't change even if the stone is a bit off round since there is no Ideal standard possibly with the way these are cut. As a dealer, one knows a diamond looks good or doesn't without consulting numbers and parameters. Your own eyes will tell you the same thing if you practice the skill of observing light performance in gems.

I recall this table and it is very helpful. My quibble is that all my favourite old cuts have teensy tiny tables close to 40%!

 

[oldminer]

The smaller than 50% table is common. I think this is partly caused by so many old mine stones having already been recut to modern cut. The ones with small table tend to have high crowns and will lose more weight in recutting than with larger tables. I think you would find that anyone cutting OM and OEC diamond reproductions currently does not often use a small table below 50%. While you can cut anything economically with Lab diamonds, the mined rough is too costly to make a good looking old cut with table under 50%.

 

[lulu_ma]

Thanks everyone for weighing in on this somewhat esoteric topic!

@Karl_K and @oldminer while you're here-can you weigh in on this question? Why do you think that so many antique stones face up whiter than their GIA color grades ( not just the spready ones)?

I have noticed that the newly cut "antique-style" stones lack the "white top" effect.

I have always been curious about this topic and wonder if there is any scientific, cut explanation.

 

[Garry H (Cut Nut)]

Late to the party!
Not much to add that Karl and Dave have not already said.
My friend Scott, the Museum Diamond guy - he is an historical purist - so for him light return is totally mute.
For me, the variations are so great, that simply using Ideal-scope, or for those who know how to interpret the tool, ASET - thats still the best way to assess performance.