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1c and 1.5c difference in diameter princess cut

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mbn

Shiny_Rock
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Sep 8, 2001
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212
I've noticed that going from 1c round to 1.5c round, there's a 1m difference, 6.5m to 7.5m. For princess, it's only .5m difference, 6m to 6.5m. Why is this?Does bigger stones have greater depth, so the weight goes there instead of toward spread for bigger diameter in princess, or because weight goes toward the 4 corners?
 

mbn

Shiny_Rock
Joined
Sep 8, 2001
Messages
212
How did you arrive at the difference in the area, how did you calculate the area?My numbers were taken from the standard that 1c princess diameter is 6m, 1.5c is 6.5 so only .5m difference.round 1c is 6.5m, 1.5c is 7.5m a whole 1m difference.
 

pricescope

Ideal_Rock
Joined
Dec 31, 1999
Messages
8,266
I just checked with DiamCalc...Princess with 69.6% total depth.
1.0ct - 5.7 x 5.7 x 3.97 mm
1.5ct - 6.52 x 6.52 x 4.53 mm
----
0.82 mm difference in the side length
10.02 mm² difference in the areaPrincess with 78.3 % total depth.
1.0ct - 5.57 x 5.57 x 4.36 mm
1.5ct - 6.38 x 6.38 x 4.99 mm
----
0.81 mm difference in the side length
9.68 mm² difference in the area
Round with 60.9% total depth.
1.0ct - 6.50 x 3.96 mm
1.5ct - 7.44 x 4.53 mm
----
0.94 mm difference in diameter
10.29 mm² difference in the areaSo yes there is a difference but not as big as 0.5 mm.Perhaps you compared diamonds with different girdle thicknesses and/or pavilion-crown proportions
 

mbn

Shiny_Rock
Joined
Sep 8, 2001
Messages
212
well, I happen to have a 1c round engagement ring already, so that's why I consider princess cut for a bigger stone w/out realizing that 1.5c princess is not that much bigger than a 1c round!
 

pricescope

Ideal_Rock
Joined
Dec 31, 1999
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8,266
Example: Princess1.0 ct: Area = 5.70mm x 5.70mm = 32.49mm²
1.5 ct: Area = 6.52mm x 6.52mm = 42.51mm²
------
Area difference = 42.51 - 32.49 = 10.02mm²
Example: Round1.0 ct: Area = PI x 6.50²/4 = 33.18 mm²
1.5 ct: Area = PI x 7.44²/4 = 43.47 mm²
------
Area difference = 43.47 - 33.18 = 10.29 mm²PI = 3.1415926
 

mbn

Shiny_Rock
Joined
Sep 8, 2001
Messages
212
so the area for 1.5c round with 7.44x4.53mm is 3.14x(7.44x7.44)/4=43 mm?Area for of 6.46x6.30=40.69mm2Difference between area of round and princess is 2.31 mm. Difference in diameter is 1.14m. Is that a big difference between the 2 shapes same size?
 

mbn

Shiny_Rock
Joined
Sep 8, 2001
Messages
212
So if same carat size round diameter is bigger than same carat size princess diameter, but total area difference is not too much, then 2 shapes would look comparable in size and spread, you think?I asked this because I have 1.13c princess who's diameter is 5.90, and I put it next to a 1c round which I dont' know dimension, and there isn't that much difference. That's why I wasn't aware back then that there was big difference in diameter between the 2 shapes same size.
 

pricescope

Ideal_Rock
Joined
Dec 31, 1999
Messages
8,266
Obviously diameter of the round stone is bigger than length of the princess but you cannot compare only length and width6.46x6.30 are just the sides of the rectangle with diagonal = 9.02mmSo if you'd compare diagonal of the rectangle and the radius of the round, princess will win
Seriously, round is more brilliant and have better spread than princess. Princess diamonds are usually cut for the weight retention and are deeper than rounds.However some people prefer princess as more elegant/modern shape.You also can consider Flanders cut that are not as deep as princess.
 

mbn

Shiny_Rock
Joined
Sep 8, 2001
Messages
212
How did you arrive at the difference in the area ?My numbers were taken from the standard that 1c princess diameter is 6m, 1.5c is 6.5 so only .5m difference.round 1c is 6.5m, 1.5c is 7.5m a whole 1m difference.
 
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