Question about diameter of my stone

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Jun 11, 2003
What should the diameter be for a 1.64 RB diamond be? I''ve seen a few that are larger than mine and am curious how diameter size impacts the quality of the diamond. I have a 1.64 carat with a 7.5-7.55 diameter. is this in the right range? how will it impact the appearance/brilliance/sparkle of my diamond?


Oct 30, 2002
A well cut round of 1.64c should have a diameter of around 7.65mm and a depth of around 4.65mm..give or take a few mm both ways.

Diameter makes a huge difference as to how your diamond is visually viewed. Check out meraj's current post on 'spread' to read more. Diameter is how the stone appears to face up to your eye.

Also keep in mind that settings can make a stone look larger or smaller. A 1c stone on a 1mm band will look larger than a 1c stone on a 2mm band. It also depends on your fingers and your hand, etc. Small hand, 1c stone looks bigger--even if its not. A friend of mine has smaller hands, she has a .75c stone that looks like a 1c. So you may be seeing stones that you think look bigger but they aren't...or maybe they are..who knows!

Good luck.


Jan 29, 2003
We thought the best way to answer your question might be with an example... This is a 1.60 carat from our inventory:

Measurements: 7.59 - 7.61 x 4.59
Total depth: 60.7%
Table diameter: 57%
Crown angle: 34.1 degrees
Pavilion angle: 40.7 degrees
Girdle: Thin to Medium, Faceted

We'd prefer that the crown angle were a little steeper, somewhere around 34.5 degrees, but the pavilion angle was right on the money and that's what makes a diamond tick... It's not so much the outside diameter of the stone that you should be concerned with, it sounds like your diamond is in the range of where it should be, but what are the critical angles that control the light? What are the crown and pavilion angles? It's possible that you're 1.64 carat has a little extra depth because of a steeper crown angle or a steeper pavilion angle or a thicker girdle and thus the outside diameter is a little smaller, that doesn't make it less desireable over a diamond with a slightly larger outside diameter... Diamonds are like people, each one is slightly different and nothing is perfect
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