Princess vs. Round Cut Size Comparison

[KrWz]

Hi all. I was just wondering if its true that a 1 carat Round Cut will appear bigger than a 1 carat Princess cut? Thanks!

 

[belle]

here is a recent thread on the comparison. try doing a search, there have been several discussions on the matter.

 

[DiamondExpert]

Here is a real life example of two AGS0, 1.57ct. stones, both VS1 color.

The Princess is G color, 6.26 x 6.26 x 4.92 mm, Table 58.4%, Total Depth 78.7%, Girdle 3.3-4.3%, AGS0 (new system)

The round is H color, 6.57x6.63x4.00 mm, Table 56%, Total Depth 60.7%, Girdle 1.2-1.7%, AGS0 (current system)

 

[Paul-Antwerp]

Hi Gary,

Could you just turn that princess with 45°?

It will change the perception.

Live long,

 

[RockDoc]

Date: 7/3/2005 3:42:52 PM
Author: Paul-Antwerp
Hi Gary,

Could you just turn that princess with 45°?

It will change the perception.

Live long,

Hi Paul....

I agree it would change the visual perception, but since most rings would have the stone set the way Gary photographed it, I am sort of curious what real meaning that would have to a consumer.

That might be only a practical view if the diamond were to be set in that position.

I could be incorrect in assuming this, but that sees apprarent to me.

Rockdoc

 

[DiamondExpert]

OK...how''s that?

I does paint a different perspective, but as Bill says, it''s not the way stones are set normally.

 

[Garry H (Cut Nut)]

It would be great if someone could find the thread where Valeria did some great stats and work on this ttopic and you could all ajourn to that place.

 

[rickyrockranger]

If a 78.9% table is an AGS0, then the cut grade on princess is meaningless.

Sorry - but when you are at 75%+ depth on a princess, you are losing a LOT of spread in the diamond.

In the real world, a princess wtih 78+% depth would be a deep cut, and undesirable.

Anyone else have any thoughts on this???

 

[JohnQuixote]

Hi RRR,

You're not alone with this reaction. It sounds crazy at first until you look at it with different eyes. Thanks to much R&D by AGS a lot has changed in maximizing light performance in princess cuts. Many current princess cuts receiving the AGS0 grade do have around a 78% depth.

First it is important to consider (and understand) that the matter of depth and spread in a princess is not the same as in a round. You can have two princess cuts with the same diameter and weight – one with a depth of 65% and the other with a depth of 75% - so a greater depth does not necessarily mean it will look smaller.

Here is a journal article by Paul Slegers, who has done much R&D towards acquiring high light performance in the new AGS grading system.

And… Here is a thread discussing particulars (it iis especially important to understand the role of P1 in all of this).

 

[rickyrockranger]

John,

That would definitely be an eye opener! Can you please show me a 65% and 75% depth princess with the same carat weight and same diameter spread?

I can''t even conceive of how that would work!!!

Really interested in this!

 

[JohnQuixote]

Date: 7/3/2005 9:14:22 PM
Author: rickyrockranger

John,

That would definitely be an eye opener! Can you please show me a 65% and 75% depth princess with the same carat weight and same diameter spread?

I can't even conceive of how that would work!!!

Really interested in this!

Ricky - certainly. Here is the scenario Paul used that helped me. For all of the examples below diameter is fixed at 6x6mm. C1 is 36.50 degrees and C2 is 31.00 degrees so crown height does not change.

Example 1: Total depth = 75.1% (P1 63 degrees, P2 43 degrees). Weight 1.32 Cts. 6x6mm.
Example 2: Total depth = 75.1% (P1 to 55 degrees). Weight is now 1.16 Cts. 6x6mm.
Example 3: Total depth = 65.3% (P1 to 59 degrees, P2 to 38.4 degrees). Weight is still 1.16 Cts. Spread is still 6x6mm.

 

[JohnQuixote]

Example 1: Total depth = 75.1% (P1 63 degrees, P2 43 degrees). Weight 1.32 Cts. 6x6mm.

 

[JohnQuixote]

Example 2: Total depth = 75.1% (P1 to 55 degrees). Weight is now 1.16 Cts. 6x6mm.

 

[JohnQuixote]

Example 3: Total depth = 65.3% (P1 to 59 degrees, P2 to 38.4 degrees). Weight is still 1.16 Cts. Spread is still 6x6mm.

 

[JohnQuixote]

Thusly, examples 2 and 3 both have the same diameter, the same crown and the same weight (the same spread). The only difference is in depth (75.1% versus 65.3%). Obviously with tweaking you can get this to a flat 75% and 65% with same spread. It's the role of P1 that really steps up in these examples.

 

[MissAva]

Very cool John! Thanks soo much for posting that, it really help to see it!

 

[JohnQuixote]

Date: 7/3/2005 7:26:31 PM
Author: Garry H (Cut Nut)
It would be great if someone could find the thread where Valeria did some great stats and work on this ttopic and you could all ajourn to that place.

Garry - Is this the thread you were thinking of?


(Matatora - you''re welcome

)

 

[belle]

Date: 7/3/2005 11:10:20 PM
Author: JohnQuixote
Garry - Is this the thread you were thinking of?

that''s it!!

well done sir john!

 

[MissAva]

allright ya''ll are just evil! I just spent 30 minutes reading that thread and I had to whip out my stats book 3 enteries down. Yikes!