Spread Question

[RLG]

Hi,
I''ve been reading this forum for about a month now and have learned so much. My question is when you are searching for a diamond to buy, one of the columns is a spread %. Is it better to have a diamond that has a negative percentage or a positive? I guess I just don''t know what that information means.
Thank you!

 

[JulieN]

It depends.

If HCA<2, and usual girdle acceptability range of thin-slt thick, then I think it becomes a question of fire vs brilliance.

You will see a % mostly in the -3 to +2 range. Honestly, THERE IS NOT MUCH DIFFERENCE between a -2 and +2. You're eyes will never be able to see the difference. Generally when spread is -4% or less, I would need a good reason to suggest it.

 

[RLG]

Thank you. I really just couldn''t figure out which was better, but from your answer it seems like its a mute point within a certain range.

 

[JulieN]

Yes, I think it is.

 

[Garry H (Cut Nut)]

For a round 1ct Tolkowsky stone of 6.47mm this is the diameter difference is 6.42mm for -2% and 6.51mm for +2%.

More important can be the difference between the edge of the diamond light return - and in the case of rounds (only) there is a slightly higher chance that a -2% stone will also have better edge light return and can there fore look like a diamond of say 5 or 10% better spread.

This is one of the reasons why HCA is weighted to give better / lower scores for prefer very slightly shallower diamonds. This BTW is not just "my preference" as many people quote - it is also based on the preferences i observe when people are selecting diamonds.

 

[lumpkin]

Oh, yeah!!! That edge to edge light return makes so much difference that you wouldn''t believe it until you see it. I love my slightly shallower diamond! It looks almost as large as an average one carat but it''s only 80 points. Gary, I am so glad I found the HCA. It was right on target for my little baby!