Part of the advertising campaign for diamond involves the "4 C's"
They are
Color
Clarity
Carat Weight
and
CUT

A lot is made of the fourth "C"- Cut- nowadays- and with good cause. The manner in which a diamond is polished really affects how it looks.
GIA grades the cut of Round Brilliant Diamonds- which certainly simplifies things for buyers.
But what about fancy shapes?
They are not graded for Cut quality by GIA.
Part of the reason is that there's so much variation within each of the shapes- unlike round, which is fairly standardized there's a huge variety of shapes that comprise "radiant cut".
Shape- that means LxW and the size of the corners- are only one aspect we need to look at.

We also need to look at how deep the diamond is, how large the table is ( that's the large flat facet on top)- and the crown and pavilion angles.
The top of the diamond is the "crown" the bottom is called "pavilion"- separating them is the "girdle"
The point at the bottom is called the "culet"
I've labeled these below



In this example, we are going to look at a stone which is a very shallow cut.  Why would they cut it this way?
The reason has to do with the available piece of rough.
it might have been a very shallow piece- or this diamond was a piece sawed off the top of an octahedron.
The stone they came up with made excellent use of the rough- I'm sure they lost a far smaller percentage than the stone I used for comparison.
Say you start with a piece of rough diamond that weighs 1.65cts- that might polish out to a 1.00ct diamond.
In this case they might have started with 1.30cts rough

You'd expect there to be some penalty visually for this.
Fancy colored diamonds are really a different animal than colorless and near colorless stones.
I did not expect to like this stone- given it's large table
ITEM #: R4354
Radiant Cut Diamond, Loose

  WEIGHT: 1.02ct
  SHAPE: Radiant Cut
  COLOR: W-X, Natural Light Yellow
  CLARITY: SI1
  MEASUREMENTS: 6.32 x 5.75 x 3.32 mm
  TOTAL DEPTH: 57.7%
  TABLE SIZE: 80(est)%
  FLUORESCENCE: FAINT

Here it is from the side


Below next to a stone with a taller crown


On many fancy shaped stone, crown height- expressed as a percentage- is sometimes considered.
Cuts like our Old Mine Brilliant stones have very tall crowns.
This stone has a crown I'd estimate at 7-8%
The stone in the diagram above has 13.5% crown height
 It might be "logical" to assume such a stone would pay a heavy price visually.
This stone belies that.
Here it is face up next to the stone I used for comparison- a fancy intense yellow 1.03ct



There certainly is a price for the cut financially.
This is a one carat stone, that looks like a carat and a third- yet costs like a 3/4ct.

The fact that it's a diamond cut to emphasize it's yellow color- which it does successfully as well, I might add- give it different parameter as compared to a colorless stone.

Summation: We can point to the weakness of a diamond like this when judged against a benchmark that values crown height.
But we can also note that the cutter was able to produce a very lively stone- with a pleasant light return and fantastic size for it's weight.

DBL - I always thought that CUT trumped all the other Cs by far!  I always thought that if you didn't have a good cut, you didn't want the diamond.  I was wrong. Thanks for the fantastic education!!!

     

Thank you for pointing that out, OMC.  And I'm so glad that we have DBL to find those gems of opportunity for us - or I would be penniless and homeless.....

It's a very good point.
There's a lot of "information" out there which purports to tell us what the "best" table size, depth, etc are.
Although the cut of this stone is unconventional, I would not say it's "badly" cut- but I suspect others might.
They'd be wrong.
BTW- the other aspect of this type of cut is the money you save- it's a large looking one carat for around $2k- and that's very hard to find

Hear!  Hear, Trink! Well said!

One might think so, Trink; but perhaps it's more a factor of those of us who have taken the plunge and own a piece from DBL.  We KNOW D's worth.

Um, only problem is, most of us can't stop with just the one! 

Brilliance: amount of light reflected.
Fire: light diffracted ("rainbow") through the stone.

A mirror is very brilliant, but not fiery at all. A prism designed to split a ray of incoming light into a rainbow is practically all fire and no brilliance.

Brilliant cut is a style of cutting where the pavilion facets start from the girdle and converge to a point (rather than being arranged in tiers parallel to the girdle, which is what is known as a step cut).

And this is the reason why I LOVE DBL!  I hope there is a little black box under the tree for me on Dec 25th!!!

Trinkette - you and OMC blow me away with your extensive knowledge of diamonds!  After reading your post I finally know why I prefer a brilliant cut to an emerald cut - I want the stone to come out and meet me!

Thank you so much!

Lovecolor - So the next time we have a play date in DBLs safe (I can see DBL shuddering as he reads this)- you get the emerald cuts and asschers, and I get the cushions and pears.  I want my diamonds to come out to meet me and play nice.  OK? 

 

OMC - Trinkette said "crystal" in her post - I'm saying "Cristal" in my post.  So, it's obvious to the casual observer that the bottle of bubbly is MINE! 

Trinkette - next time we're both in NYC, we've got to go out to lunch, and I'll treat if you teach me more about diamonds!!!