CA/PA combos. (34/40.6) vs (34.5/40.8) vs (35/41)

[mrfat]

Let's assume all stones have similar specs aside from CA/PA. GIA triple EX. Assume 61.5% depth, 56% table, 75% LGF, 50% star.

Here we have a Shallow (34/40.6) vs the Ideal(34.5/40. vs Steep/Deep cut(35/41). What will the visual differences be? How do brilliance and fire differ amongst these? In noon day sunlight how will they appear? In an office environment with overhead fluorescent lights?

Here's my understanding but correct me if I'm wrong

The (34/40.6)
-shallow cut diamond
-should have better brilliance than fire?
-can have obstruction issues if viewed closely. Even at arm's length could have center obstruction issues. Arrows appear dark so center looks dark.


The (34.5/40.
-ideal proportions or close. Good mix of brilliance and fire.


The (35/41)
-Steep/Deep so potential for light loss under the table. Will also result in center looking dark
-Needs to be kept clean or more light loss?
-Should produce more fire and brilliance?

 

[diamondseeker2006]

I don't call 35/41 steep deep. I have had one and it had an excellent idealscope image. I'd want light return images on all of these. You are making generalizations that are not true of all stones with those measurements. They are all within a range that are worth exploring further. I have also had a 34.5-40.8 stone and I will tell you there was absolutely NO discernible difference in fire and it certainly wasn't less brilliant. You just cannot make generalizations like this. Get idealscope or ASET images on all stones that score near or below 2 on the HCA and that is how you see if there is leakage or great light return. Other than that, people have different preferences, but you usually can't really appreciate the differences unless you see a lot of diamonds.

 

[Dancing Fire]

w/o I-scope or ASET images a 56% table, 34.5 X 40.8 is a safe bet, but of course PSers prefer to see the images...

 

[Paul-Antwerp]

I agree with other posters that your expectations are too general.

In fact, as a cutter, I am capable of producing magnificent brightness and fire in all these combinations.

The problem is that we are faced with two realities in assessing the effects of cut-quality:
- one could study existing diamonds, leading to incorrect generalizations, because the actual pool of diamonds does not correctly reflect what is possible.
- one could study what is theoretically possible in cut-quality, leading to incorrect generalizations, because the results are not in sync with the actual pool of diamonds.

So, you might find people confirming your expectations based upon experience with actual diamonds (and, I must add, a bit of exaggeration). I however wholeheartedly disagree.

Live long,

 

[mrfat]

Thanks for the info. I couldn't tell any difference between these various combos either. They all had red reflector images that showed no leakage under the table or really anywhere else. I'm not sure if they were firescope or idealscope images but I don't know if that really matters.


Of course these were all viewed under jewelry store lighting so I was wondering how different lighting environments might change their appearance. I know 34.5/40.8 might be safer but the other two looked great as well and they were a little bit cheaper.

 

[Paul-Antwerp]

I hink that you are misunderstanding my reply.

With either of these average combos, I can produce fantastically performing AND average performing diamonds. The difficulty of achieving either result differs a little bit depending upon which combo, but all is still possible.

This does not mean that these combos are equal, they are not. It means that basing yourself on these combos only is insufficient to come to definite conclusions.

Live long,

 

[mrfat]

The combos aren't equal so does that mean they'll result in different personalities?

I don't know all the fine details about diamonds so I was wondering if any of these combos was a reason to exclude any. And beyond that since they are different in proportions how would that translate to their personality.


These diamonds seemed to be well performing diamonds via what the gemologist said and tried to convey to me with the scope images. What I'm wondering is how these different proportions translate into different light performance characteristics or personalities.

 

[gr8leo87]

I can tell you that no two 34/40.6 will have exact same personalities.

All those numbers are within very good range. You can perhaps also add 35.5/40.6 and 36.0/40.6 to your list.

 

[Karl_K]

The answer to your question is complex.
Well cut examples of each of those proportion sets would have a different personality or look.
However it is lighting condition dependent and to explain the differences would need a lot of words and time with those specific diamonds in hand and then would degrade into an argument over wording that goes nowhere for 500 pages or until everyone gets sick of it so one person can think they won.....
In other words not happening......

My advice when looking at such a trio in person is to use as many lighting conditions as possible and block the spot/led lights if in a store. Store lighting is designed to make even the poorest cut diamonds look good and is not good lighting to pick up the differences in personality.