Jump to content

trade-offs among characteristics


Recommended Posts

I'm soon to purchase a Princess Cut diamond for an engagement ring to be set in white gold. Below are the characteristics of a diamond I am considering buying:


Size: 1.15 carat

Cut: Very good

Color: E

Clarity: VS1

Depth/Table: 70.3/67.0

Flourescence: None

Length to width ratio: 1.01

Report: GIA


This diamond is approximately $6.5k. I'm willing to spend approx. $500-1000 additional to get a higher quality diamond.


Given this shape and the white gold setting, can someone provide guidance on which characteristic(s) I should consider upgrading first?


Also, are there any obvious trade-offs in characteristics I should consider in order to get a higher quality diamond, i.e. decreasing the size and color in order to increase the cut or clarity?


I understand this is a difficult question to answer, but the only indicator I have right now is price and I've only seen a couple of diamonds in my lifetime, so your expert advice would be greatly appreciated.

Link to comment
Share on other sites

From the initial numbers it looks like you have a good beginning. I would add light performance analysis to the equation to make sure you don't end up with a VS1 E dud as far as light return goes though.


It's very hard to tell how bright the stone would be with only a table and total depth. It would be like buying a house by only going by the outside dimensions of 40 x 40 for example. It won't tell you how the interior walls and the rest of the house look like.


To learn more about light performance, go to this site:



Link to comment
Share on other sites

GIA grading reports for Princess cuts doesn't include an option of "Cut: Very Good". If your report contains this, it's not from GIA. See GIA's website for samples of what their various reports look like. If you've got a counterfeit report, kill the deal. Assuming that this information didn't come from the lab report, where did you get it and what scale is it based on?



Link to comment
Share on other sites

Hopefully, this helps:


Symmetry: Very good

Polish: Very good

Girdle: Thick

Culet: None

Fluorescence: None

Measurements: 5.81 x 5.73 x 4.03 mm

Length/width ratio: 1.01


As for the cut designation, I guess if it is not GIA, then it is that of bluenile.com. When it comes to trade-offs, there is a category called ideal, which is above very good.

Link to comment
Share on other sites

If you're buying from BlueNile you can be confident that nothing is counterfeit.


They are surprisingly unclear about what they mean by a 'very good' cut. Their definition of 'ideal' involves 3 or 4 parameters falling within certain ranges using a system that’s unique to them but I see nothing on their site to indicate any other grades or, for example, what the difference is between ‘very good’ and ‘good’. It seems to be a Boolean system of ideal and non-ideal where the value of idealness is highly suspect in the first place. Maybe I’m missing something but this grade looks useless.


The rest looks promising. Since we know it’s from BN, I’ll assume you haven’t seen it and, since it’s not in their signature series, I suspect they haven’t either. Somebody somewhere claims it’s pretty good. If that’s enough assurance for you, BN does have a pretty agreeable return policy if it doesn’t work out.



Link to comment
Share on other sites

As an example:


This diamond is about the same size and the same price. While the cut went from very good to signature idea (best cut classification available from BN), the following characteristics are 'worse':


Color: G

Clarity: SI1

Depth/Table: 65.9/69.0

Length to Width: 1.01

Symmetry: Very Good

Polish: Excellent

Girdle: Medium to Slightly Thick

Culet: None

Fluorescence: None

Measurements: 6.00 x 5.93 x 3.91 mm

Crown height: 9%


I'm confused as to which is the 'better' diamond. What do I gain by getting one over the other?

Link to comment
Share on other sites

Here's a page describing Blue Nile cut: http://www.bluenile.com/diamond_grading.asp

What I'm looking for is the BN/GCAL scale for cut grading of princesses. The page you referenced only mentions their scale for rounds. GIA doesn't have one and they aren't using the one from AGSL. I'm confusted too.


They mention the rules for 'signature' grading here but they aren't even consistent about that. Check the link to learn more. Does a signature crown need to be 8% or 8.5%?




Link to comment
Share on other sites

I'm not trying to be thick but I'm still missing it. How many steps are in the scale for cut grading of princess cuts, what do they measure and what are the dividing factors between the various grades? I'm reasonably well informed on these things but the BN/GCAL people use their own special system and they aren't very forthcoming with information about it. I think you're just supposed to take their word for it and buy an SI.


'Signature ideal' is somebody's idea of a pretty good cut and they list the attributes that are being considered as: Crown Height, Table, Shape, Overall depth, symmetry and polish. The images that claim to show 'optical brilliance' and 'optical symmetry' don't seem to have anything to do with it. Do they even do this on princess cuts? Your post saying that you were offered a stone with 'very good' is the only hint that the scale contains more than 'signature ideal' and 'other'.



Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


  • Create New...