Your Guide To “Excellent” Cut Fancy-shape Diamonds

If you were searching for a true “Excellent” Cut Fancy-shape Diamond before 2022, you’d be up the creek without a paddle. Fancy-shape Diamonds (any shape that’s not a Round Brilliant) did not receive an official Cut Grade on their Grading Report (aka Certificate) til then. HUGE problem. Cut Grade denotes how much light a Diamond returns. If you were shopping for a Diamond online, how were you supposed to tell what’s a well-cut, brilliant Diamond and what looks like a candy gem from a gum-ball machine at a pizza parlor??

You’d have to rely on your jeweler, and that’s a dangerous game. For years, there was no objective way to compare Fancy-shape Diamonds on light return. Now there is. In this post, we’ll dive in to how the IGI grades Fancy-shape Diamonds for an official Cut Grade, the criteria for an “Excellent” Cut Fancy-shape Diamond, and what to do if no official “Excellent” Cut Diamond exists for the size and shape you want.

IGI issues Cut Grades for Fancy-shape (non-Round) Diamonds

In 2022, the IGI had the stones to issue actual Cut Grades on their Diamond Grading Reports for Fancy-shape Diamonds. HUGE news. They’re the first Diamond Grading Lab to do so. Why are they the first? Because grading for light return on a non-Round Diamond is freaking hard. Why is grading Cut on Fancy-shape Diamonds hard? It’s difficult to objectively compare and grade the light returned by Diamonds with different ratios. For example, Rounds are always perfect circles and exhibit very little light leakage when perfectly-cut, so they’ve always had an official Cut Grade on their Reports. But, an Oval can have a 1.35 ratio, a 1.42, 1.46, 1.50 (or even higher) Length/Width ratio. Comparing these is hard. But the IGI loves hard. They live for it. They’re the David Goggins of Diamond Grading.

What makes an “Excellent” Cut Fancy-shape Diamond?

Let’s walk through this step-by-step First, let me link IGI’s Guidelines for an “Excellent” Cut Fancy-shape Diamond.
It’s attached below as a PDF also.

Page 2 of the Guide breaks down the grading process, let’s have a look together at how a Fancy-shape Diamond can receive an official “Excellent” Cut Grade.

There are 4 stages a Diamond must pass to receive an “Excellent” Cut Grade.

1. Its marks for Polish and Symmetry must be “Very Good” or “Excellent”
2. It must meet all the Proportions requirements of an “Excellent” Cut Diamond of its shape
3. It must meet the Additional Requirements of a Diamond that shape. For example, if it’s an Oval, it must have a negligible “bowtie” (no noticeable dark shadows across the center of the Diamond).
4. The Diamond must exhibit maximum light return and minimum shadows.

Let’s look at an official “Excellent” Cut Oval Diamond we have in the shop

This one’s a beauty. 4.01 carat IGI graded Oval-shape Lab-Grown Diamond. Crisp “E” Color and completely eye-clean “VS1” Clarity (you need magnification to see any of those imperfections, can’t see them with your naked eye). And of course, official “Excellent” Cut Grade (shown on the Report). How did it get the official “Excellent” Cut Grade?

1. Polish and Symmetry both “Excellent” ✅
2. Proportions for an Oval are on Page 5 of the PDF. Table (60%), Depth (61.7%), Crown Height (14.5%), Pavilion Depth (43.5%), L/W ratio (1.45) and Girdle (Medium to Slightly Thick) are all with “Excellent” Cut Proportion ranges for an Oval ✅
3. On the bottom of Page 5 are the Guidelines is the Additional Requirements section for an Oval. This one has no noticeable bowtie (lots of light return and no dark shadows across the middle) ✅
4. This Diamond’s sparking like a firework on America’s birthday. Maximum light return ✅ Take a look at this video of the Diamond here.

And the price? This gorgeous Diamond’s $2,400.

What if I can’t find a true “Excellent” Cut Fancy-shape Diamond for the shape and size I want?

There may not always be a true “Excellent” Cut Fancy-shape Diamond to meet the exact specs you want. In fact, the vast majority of Fancy-shape Diamonds do not have an official Cut Grade listed! Most growers don’t elect to have their Fancy-shape Diamonds graded for “Cut” since it costs more money and takes more time. And of course, if the Diamond is poorly-cut, it’s unlikely the grower will elect to have a “Good”, “Fair” or “Poor” Cut Grade printed on the Report. So, if there’s no official “Excellent” Cut option for the Fancy-shape Diamond you’d like, here’s what you do:

1. Make sure all Proportions are within “Excellent” Cut range and that Polish and Symmetry are both “Excellent” as well.
2. Ask your jeweler for an ASET Scope photo of the Diamond, to confirm there’s no bowtie. An Oval with a bowtie will have blue as the primary color across the middle under ASET, a well-cut Diamond will have red as the primary color instead.
3. Ask your jeweler for some videos in Natural and Studio lighting to see how much light the Diamond reflects.

Let’s walk through an example together below.

We have this one in the shop as well. Again, a gorgeous Diamond! Let’s run through the same steps the IGI uses to grade Cut.

1. Polish and Symmetry both “Excellent” ✅
2. Proportions for an Oval are on Page 5 of the PDF. Table (60%), Depth (62.6%), Crown Height (14%), Pavilion Depth (44.5%), L/W ratio (1.43) and Girdle (Medium to Slightly Thick) are all with “Excellent” Cut Proportion ranges for an Oval ✅
3. Now for the Additional Requirements section. Is there a significant bowtie? Absolutely not. The Diamond’s clear across the middle, as you’ll see in photos in the next section. ✅
4. Last and definitely not least, we’ll look at light return under an ASET Scope, Natural lighting and Studio lighting to see if this Diamond’s sparkling at the same level as the “Excellent” Cut above.

This beautiful Diamond is $2,000.

How do a true “Excellent” Cut Oval and an Oval with “Excellent” Cut Proportions (but no official Cut Grade) compare?

First, under ASET Scope.

This is the 4.01 carat official “Excellent” Cut.

• Red is the primary color across the center, confirming a negligible bowtie
• Green and red shades through the rest of the Diamond indicate areas of maximum and average light return, respectively.
• Notice how the overall Diamond under ASET Scope is “murky” and darker all around. Seems counterintuitive, but that murky green hue means average light return is coming from those areas. Under ASET, clear areas mean no light return!

This is the 4.01 carat with perfect Proportions but no official Cut Grade.

• Red is the primary color across the center, confirming a negligible bowtie
• Some red on the North and South ends as well!
• Notice how the overall shade of this Diamond under ASET is lighter (almost clear) compared to the official “Excellent” Cut. Under ASET, clear areas signify parts of the Diamond that aren’t returning light!

Next, under indoor and outdoor lighting.
The official “Excellent” Cut is on the bottom in both photos, and you can see that’s it slightly brighter.

If you’d like an Engagement Ring with a Fancy-shape (non-Round Brilliant) Diamond in the center, always aim for one with an official “Excellent” Cut Grade. This eliminates you having to guess how much light the Diamond returns; an official “Excellent” Cut Diamond is returning maximum light.

Now, there’s a chance no official “Excellent” Cut Diamond exists for the shape and size you’d like. Less popular shapes (Marquise and Hearts) and step-cut shapes (Emerald-cuts and Asschers) are less likely to be sent in for official Cut Grading. In this case, like we talked about above, make sure all Proportions match the “Excellent” Cut Guidelines, then ask for ASET images and some images in natural lighting to confirm the Diamond is sparkling well and doesn’t have a significant bowtie.