In this guide, we’ll walk you through what diamond cut really means, why it matters, and how to make sure you’re getting maximum brilliance for your budget.
Including what to look for, what to avoid, and how to make your diamond sparkle harder than your in-laws’ opinions.
When you’re shopping for a diamond - whether it’s for a proposal, an upgrade, or a well-deserved “I love me” moment - cut is the most important factor to get right.
It’s not about the shape (we’ll explain), or whether it’s lab-grown or mined. Cut has the biggest impact on how your diamond looks, performs, and - yes - sparkles.
So, if you’re weighing carat size and clarity, but haven’t paid much attention to cut, you might end up with a diamond that sounds good on paper but looks surprisingly... dull.
In this guide, we’ll walk you through what diamond cut really means, why it matters, and how to make sure you’re getting maximum brilliance for your budget.
Let’s cut to the chase.
In this article...
- What Is a Diamond Cut?
- Whats The Difference Between Diamond Cut and Shape?
- How Are Diamonds Cut?
- How Does Diamond Cut Affect Sparkle?
- Lab Grown Vs Natural Diamonds Does Cut Quality Differ?
- How Is Diamond Cut Quality Graded?
- Why High Quality Cuts Are Worth It
- Which Diamond Cut Sparkles The Most?
- Can A Diamonds Cut Affect Its Colour?
- The Right Diamond Cut Tips for Picking the Perfect Cut
What Is a Diamond Cut?
Diamond cut refers to how well a diamond has been shaped and faceted. It’s not about the outer shape (like round or oval), but the stone’s proportions, angles, symmetry, and polish.
These factors determine how light moves through the diamond - and how much of that light bounces back into your eyes.
A well-cut diamond reflects light beautifully and looks vibrant. A poorly cut diamond? It can look flat, lifeless, and far less impressive than its certificate suggests.
The Four Cs, revisited
Yes, cut is one of the famous Four Cs (alongside carat, clarity, and color) - but it’s the only one that directly affects a diamond’s sparkle.
A smaller, well-cut diamond will often outshine a larger, poorly cut one. If you're going to prioritize anything, make it this.
Whats The Difference Between Diamond Cut and Shape?
People often use the words cut and shape interchangeably, but they’re not the same thing.
Here’s a quick breakdown:
Cut |
Shape |
|
Quality of the diamond’s proportions, symmetry, and polish |
The outline or silhouette of the diamond |
|
Impacts how much the diamond sparkles |
Impacts the overall style and appearance |
So, “round brilliant” refers to the diamond’s shape i.e. its outline or silhouette. But just because a diamond is a round brilliant doesn’t automatically mean it’s well-cut.
Cut refers to how well the stone’s proportions, symmetry, and polish maximize light performance.
Think of shape as the style, and cut as the craftsmanship behind how that shape performs.
How Are Diamonds Cut?
Cutting a diamond is a mix of science, art, and very expensive equipment.
Here’s how it works:
Planning: Experts scan the rough stone to decide the best way to cut it - balancing carat weight, shape, and light performance.
Cleaving or sawing: The rough diamond is divided into workable pieces.
Bruting: The diamond is shaped into a round outline (or another desired shape).
Polishing: Facets are added to maximize brilliance.
Final inspection: Quality is checked for symmetry, proportions, and polish.
Each step has a major impact on the diamond’s value. For example, a cutter might sacrifice carat weight to achieve better brilliance. You win some sparkle, you lose some size.
How Does Diamond Cut Affect Sparkle?
Cut is responsible for three key things:
Brilliance: The white light reflected from the diamond’s surface.
Fire: The rainbow flashes that come from inside the diamond.
Scintillation: The sparkle effect when the diamond (or you) moves.
A poorly cut diamond leaks light out the sides or bottom, which dulls the effect.
That means you could have a high-carat, flawless stone that still looks underwhelming if the cut isn’t up to standard.
Lab-Grown Vs. Natural Diamonds: Does Cut Quality Differ?
In terms of grading and sparkle, cut matters just as much for lab-grown diamonds as it does for natural ones.
In fact, lab-grown diamonds are often cut to higher standards because the rough material is more affordable. That gives cutters more freedom to optimize for brilliance rather than carat weight. So yes - lab or mined, cut still reigns supreme.
Want to dig deeper? Read our guide on lab-grown vs. mined diamonds.
How Is Diamond Cut Quality Graded?
Cut grading is most consistent for round brilliant diamonds, and the GIA (Gemological Institute of America) uses the following scale:
|
Cut Grade |
Description |
|
Excellent |
Represents the top tier of diamond cuts, providing maximum brilliance and light performance. |
|
Ideal |
Ideal cuts are proportioned to refract most of the light entering them, however ‘ideal’ is not an official grade by GIA. This is used to describe a well-cut diamond as a general term. |
|
Very Good |
Diamonds in this category reflect most of the light that enters them, producing a good deal of brilliance. Slightly less precise than ideal cuts. |
|
Good |
Good cut diamonds offer a decent amount of brilliance and fire. They are cut to balance quality and size at a more affordable price. |
|
Fair |
A fair cut diamond will still be quality but allows more light to escape from the sides and bottom. It's less brilliant compared to higher grades. |
|
Poor |
Diamonds with a poor cut grade lose most of the light out the sides and bottom, appearing dull and lifeless. These are often cut to maximize carat weight over brilliance. |
For fancy shapes (like oval, pear, emerald, cushion), cut grading is less standardized.
That’s why it’s important to look beyond the label - check proportions, symmetry, and light performance.
A few helpful tips:
Only about 3% of diamonds receive an “Excellent” cut grade.
Always review the GIA certificate, and ask to see the diamond under lighting conditions.
Want help reading a certificate? Here’s our guide on GIA certifications.
Excellent Cut
An Excellent cut diamond is a masterpiece of precision.
These diamonds are cut to reflect nearly all light that enters them, resulting in exceptional brilliance and fire.
The angles and finishing of an Excellent cut diamond ensure that it displays a vivid sparkle and a beautiful pattern of bright and dark areas.
Consider this the A-lister of diamond cuts, the kind that turns heads and sparks conversations.
Choosing an Excellent cut diamond means getting the best in light performance.
Very Good Cut
These diamonds reflect most of the light that enters them, producing superior brilliance.
While they are cut for slightly more weight retention than the absolute precision of an Excellent cut, they still provide a high degree of fire and sparkle.
A Very Good cut diamond is often an intelligent choice for the savvy buyer who wants a stunning gem at a slightly lower price than an Excellent cut.
Good Cut Grade
Good cut diamonds are the workhorses of the diamond world.
These stones offer quality performance, with much of the light that enters being reflected back.
Although the craftsmanship on a Good cut grade diamond isn't as meticulous as higher grades, a Good cut diamond still offers brightness and can appear lovely to the untrained eye.
They're priced lower than their more illustrious counterparts, making them an appealing choice for those on a budget who still desire sparkle and size.
Fair Cut Grade
These stones still emit a fair amount of light but direct a more significant portion out the sides and bottom, reducing the perceived fire and brilliance.
They are often deeper or shallower than the ideal proportions, making the diamond appear smaller with its weight.
Fair cut diamonds are generally best suited for smaller carat weights or diamonds set in pieces where sparkle is not the primary concern.
Poor Cut Grade
Lastly, we have the Poor cut diamonds, which deliver an underwhelming performance, as the name implies.
These diamonds allow most light to escape from the sides and bottom, resulting in a dull and lifeless appearance.
Poor cut diamonds lack the fire, brilliance, and scintillation that diamonds are renowned for, and they often appear glassy or muted.
They are priced considerably lower, reflecting their lackluster show of light.
Why High-Quality Diamond Cuts Are Worth It
Choosing a better cut gives you:
- Stronger sparkle (which you’ll see even in soft lighting)
- A larger appearance (thanks to all that light reflection)
- Better long-term value (because brilliance never goes out of style)
While an Excellent cut will generally cost more, a Very Good cut can still offer excellent light performance at a slightly lower price point.
Compare in person whenever possible to see the difference.
Which Diamond Cut Sparkles The Most?
The round brilliant cut is hands-down the most sparkly.
With 57-58 facets designed to reflect maximum light, it’s the classic choice for good reason.
Other contenders for high sparkle:
Princess cut: Crisp edges with lots of fire.
Cushion cut: Rounded corners and vintage elegance.
Radiant cut: Angular brilliance with extra edge.
Just remember: the cut quality is what matters most, not just the shape.
Can A Diamond’s Cut Affect Its Color?
Yes - but not in the way you might think.
Cut doesn’t change a diamond’s actual color grade, but it can change how the color appears.
A well-cut diamond reflects more white light, which can help mask yellow undertones in slightly lower color grades.
So if you’re working with a budget, a better cut can allow you to go a few steps lower in color without a visible drop in beauty. Smart move.
The Right Diamond Cut: Tips for Picking the Perfect Cut
Not sure how to prioritize your decision? Try this checklist:
- Set your budget
- Make cut quality your top priority
- Look for a GIA-certified diamond
- Compare diamonds side-by-side for sparkle
- Balance carat weight with cut and color
- Don’t be afraid to ask questions - this is a big purchase
And if you want expert help (without the pressure), we’re here for that too.
We’re not saying your diamond choice defines your personality… but if it did:
Round: Classic, timeless, not here for trends.
Princess: Bold, modern, and slightly dramatic - in the best way.
Cushion: Romantic, vintage-inspired, probably owns a collection of candles.
Emerald: Elegant, refined, and loves clean lines.
Oval: Trend-forward, cool without trying.
Radiant: Maximalist. Sparkle is a lifestyle.
Final Thoughts: Let's Find Your Perfect Cut
Cut isn’t just another box to check - it’s what makes your diamond look like a diamond.
It’s the difference between a stone that quietly exists and one that turns heads every time you lift your hand.
At Ben Garelick, we’re here to help you find the perfect cut, shape, and setting - without pressure, jargon, or guesswork.
Want to see how sparkle really looks in person?
Contact us today, and let our diamond experts help you find the one that’s as brilliant as your love story.
