face up size princess v. RB

[Cyren]

Last night I was looking at my two best friend''s rings side by side, since I''ve started lurking around here I’ve become totally fascinated with diamonds

, and I asked about the specs, one was a 1 ct center princess and the other a .75 ct RB, and they faced up the same size. I sure my friend with the RB knows all her specs and I’m confident hers is .75, but I was wondering more about the princess. I know princess cuts do face up smaller, but would it really face up a similar size to a RB that’s a full quarter carat smaller? Maybe the princess isn’t really a full ct?

 

[redhawk]

i am very new to this forum, but have learned while shopping for a diamond this past week that the ctw is only the weight and that based on the depth and table that a .75 ct rb could face up larger than a 1 ct princess.

 

[belle]

most princesses are cut for weight. this doesn''t mean ''face up'' size, but carat weight size. carat weight and face up size do not always correspond like they should, especially if the cut is not the very best. you could have to diamonds of the exact same shape and carat weight that are different sizes due to the cut, so it is a little difficult to judge them accurately just on carat weight. it is true however, that princess cuts face up smaller than rounds.

here is an example of a round compared to a princess of the exact same weight...

 

[belle]

here is a .75 round next to a 1.00 princess

 

[Gypsy]

Tell you what. Go to WF and look at the princesses... at the mm size of them at 1 carat. THen look at the .75 ish rounds and the MM size. If the princess is a 5.8 x 5.8 to 6 x 6 ish mm size ... that''s right about where a round 3/4ish carat faces up when well cut. Go see for yourself.

 

[DiamondExpert]

1.57ct. each - orientation can be important in apparent relative face up size...

 

[DiamondExpert]

...and with the Princess at 45deg.

 

[Paul-Antwerp]

Gary,

Very true indeed. The orientation can be very deceptive, and a human mind can see geometrical figures very differently than simple arithmetics would prove them to be.

Although they have smaller surface, I know many people who consider them bigger (broader) for the same size.

Live long,

 

[diamondsrock]

it is interesting how the mind perceives things.
In that first photo the princess looks smaller, but in the second with it tilted it looks bigger than the rb.
Weird!

 

[Snooper]

Very interesting Gary and Paul!! Thanks! I don''t know much about rounds, as my focus has been on fancies.

 

[Rhino]

Ok ... here''s some interesting data.

Paul ... if you recall a while back when you wrote your article on this subject in the journal I had expressed I had some info on this you''d find interesting. Here''s some of what I was talking about. Perhaps I can add an addendum or something cause this is VERY interesting.

I took two stones I have here in stock. One is an H&A round AGS Ideal 1.264ct G VS2 the other is an AGS Ideal princess 1.262ct G VS1. Virtually identical in the weight.

With our Sarin we have the ability to pull up all sorts of ungodly measurements and in our Manufacturers Report we can see data that is not posted otherwise in a typical Sarin analysis or lab report. There is some valuable information here which this poster and others interested in squares would find of keen interest I believe.

In the below attachment is our personal mnf report generated on the round. Next I''ll post the princess cut with some commentary/observations.

 

[Rhino]

Here''s the same report on the 1.262ct princess.

Things to take note of in this report.

a. Diameter measurements are taken from both corner to corner and side to side.
b. The *average diameter* is an average of all the measurements regarding the entire circumference of a princess (corners and sides).
c. In these calculations the total depth percentage is based on this *new* average diameter.
d. What some might consider the true depth percentage is reported here on this princess cut as being 59.5% 75.6%
e. What some might consider the true average diameter is reported as being 7.4mm. on the 1.26ct round the average diameter is 6.94mm.

So ... here we have an ideal princess cut vs an ideal round and when we look at all the measurements on the princess ... one could argue that the princess with the reported 75.6% depth percentage is more spready than the ideal round with the reported 61.7% depth. I''ll snap off a shot of these 2 side by side and see if the visual confirms.

Interesting stuff eh?

 

[Rhino]

Here''s the Sarin showing the most typical dimensions seen. Standard length and width measurements, l/w ratio and depth percentage. I have additional P1, P2, C1 and C2 angles included in these reports for personal use.