So I’ve been combing through diamonds over the last several weeks trying to find one with great stats as well as something that passes the eye test.
For my first pass with a diamond, I usually judge by your picture “Buy a Diamond that Looks like this” on your Education page – https://www.diamondscreener.com/education/a-simple-guide-to-buying-a-round-diamond/
If it looks to have clearly defined “pinwheel” lines and good contrast, I check the Cut Estimator to verify. But on some diamonds with very good contrast look, the cut estimator doesn’t seem to agree.
Take this guy for example: https://www.jamesallen.com/loose-diamonds/round-cut/0.80-carat-f-color-vs1-clarity-excellent-cut-sku-3716848?a_aid=55f8cd4e21a11
Appearance head-on has very good distinct lines, clear pinwheel. But Cut Estimator rates it only on the GIA edge.
So what gives here?
btw – thank you for this AWESOME website. This has made engagement ring shopping 1000x easier than I imagined and I am so much more informed thanks to your simple yet informative guides.
Hi, thanks for the feedback and I’m glad you found my site helpful.
I think this diamond is an excellent choice. There’s nothing questionable about the dimensions. The contour is inclusive, so this is still GIA Ex and the diamond has optimal proportions.
The borders of GIA Ex are somewhat arbitrarily defined with a long horizontal line at the 40.6 pavilion angle. What really matters is that it’s still on the main cutter’s line (http://www.agslab.com/spie/spie_lo_res.pdf, figure 23). This is a case where you can trust your eye and see that it has good proportions and good optical symmetry.