HI Everyone!
Welcome MB, and thanks for posting a great question.

I do not view GIA's comment on crown angles as a "warning" per se.

It really goes to how the cut of a diamond is viewed.
Clearly there's an urge to somehow "calibrate" the grade of the cut of a diamond.

Personally, I feel that such efforts really miss the point.
You can see the results in the "cut grades" issued by GIA and AGS.
There are many cases of a stone with a "lesser" cut grade being more attractive to observers.
The tests that measure light return are in this same category.

What difference does it make if a diamond "returns more light" if you don;t like the way it looks?
Fancy Colors are a perfect example of this.
Surely an Intense Yellow will "return" less light as compared to a D color.
However many people would find the yellow stone far more attractive.

Many of the decisions made by the best cutters of Fancy Colored Diamonds are done using the rough diamond as a guideline.
They have high tech machines that measure the rough allowing the cutter to precisely plot out what the finished stone will look like- and how much loss they will suffer from the rough.

However once the stone is finished, and it's sent to GIA for a grade, additional work may be done.
Sometimes one facet's alignment can cause an upgrade of a shade in color. This is why a cutter must be able to "think on his feet" and adjust the cut based on a multitude of factors.

I have noticed that many fancy colors have larger tables- with no adverse affects on many cases.
A high crown, and low depth is also a combination we've seen on many occasions with no adverse affect at all.
The stone below is a great example.
The GIA report has a comment that the crown angles are greater than 40 degrees.
Depth is 59.3%.
The stone looks every bit as large as it's weight- and it's "face up" is glorious!

The bottom line, for me, is that a stone's visual attributes are what to look at.


A good analogy- just because a man is 6 ft 2 inches tall with green eyes and weighs 195 lbs does not mean he will be seen as attractive by all women.