I’ve looked at hundreds of thousands of diamonds over my career, and I can tell you that some of the most spectacular diamonds I’ve ever seen were not the ones with the highest color or clarity grades. And conversely, I’ve seen plenty of diamonds with “impressive” grading reports that I would never recommend to a client. You can put two stones with nearly identical carat weights, color grades, and clarity grades next to each other, and one can be electric while the other does very little for me.
Why? Because a diamond’s beauty has so much to do with how it handles light and the science behind sparkle is actually pretty extraordinary, so let’s get into it.
The Three Things That Make a Diamond Dazzle
First, a little diamond education! What we casually refer to as “sparkle” is actually a combination of three distinct optical effects. And once you understand the difference, you’ll start looking at diamonds in an entirely new way.
Brilliance: This is the white light that a diamond returns to your eye. It’s what gives a beautifully cut diamond that wonderful brightness, even before you start moving it around. And here's something worth remembering: a diamond doesn't produce light. Its facets and proportions determine how effectively it can capture the light around it and send it back to you.
Fire: My personal favorite to point out to clients! These are those little flashes of red, blue, orange, and green that appear when light passes through a diamond and separates into its spectral colors. The scientific term is dispersion, and it's responsible for those wonderful rainbow flashes you sometimes catch from across the room. Yes, a completely colorless diamond can produce all that color!
Scintillation: This is where things get really exciting. Scintillation describes the flashes of light and shifting patterns of brightness and darkness you see as a diamond moves. It's what makes one diamond look like it's practically dancing on your finger while another seems relatively quiet. And believe it or not, the darker areas actually matter! That contrast helps make the bright flashes appear even more dramatic.
The really interesting part is that two diamonds can have very different combinations of brilliance, fire, and scintillation. Some produce big, bold flashes of light, while others have a much finer, more rapid sparkle. It's one of the reasons I find comparing diamonds so fascinating.
Why I'm So Particular About Cut
A diamond is essentially an incredibly sophisticated little optical instrument. Every facet has a job to do, and the relationship between those facets determines how light travels through the stone.
Take a round brilliant, for example. Its crown angle, pavilion angle, table size, and depth all work together to influence how much light comes back through the top of the diamond. But when they're not? Light can escape through the bottom or sides instead of returning to your eye. We call this light leakage, and it can make an otherwise impressive diamond look surprisingly dull.
This is why I would take a beautifully cut two-carat diamond over a poorly cut three-carat diamond any day of the week. A larger diamond that doesn't handle light well is not suddenly going to become more beautiful because there's more of it!
Not All Diamond Cuts Are Supposed to Sparkle Alike
An emerald cut is not supposed to sparkle like a round brilliant. And I wouldn't want it to!
Emerald cuts have those wonderful long, step-cut facets that create broad flashes of light and a hall-of-mirrors effect. When you find a really beautiful one, the effect is almost hypnotic. You're looking for crisp facet patterns, beautiful contrast, and those big flashes of light that move through the stone.
Ovals are a completely different story. I spend an enormous amount of time evaluating their outlines, proportions, and bow ties. A bow tie is the darker, bow-shaped area that can appear across the center of an elongated diamond. Some degree of contrast is normal, but a particularly dark or distracting bow tie can completely change how an oval looks on the hand.
And cushions! There is an extraordinary amount of variation within that category alone. Some have broad, chunky flashes reminiscent of antique diamonds, while others have a much finer, almost crushed-ice appearance. I have very strong opinions about cushion cuts, and the grading report is never going to tell me everything I want to know about one.
The point is that there is no single formula for a beautiful diamond. Different cuts have different personalities, and understanding what makes each one exceptional is a huge part of the sourcing process.
So, What Should You Actually Prioritize?
If I could give one piece of advice to anyone shopping for a diamond, it would be this: don't get so caught up in the grading report that you overlook the beauty of the diamond itself.
Of course, carat weight, color, clarity, and cut all matter. But I see people get so fixated on achieving a particular combination of grades that they lose sight of what they're actually trying to buy: an extraordinarily beautiful diamond!
Sometimes that means choosing a slightly lower color grade to get a much better cut. Sometimes it means looking at a few different facet patterns within the same shape. And sometimes it means passing on a diamond that looks wonderful on paper because something about it just isn't quite right in person.
That's the part of sourcing that I find endlessly fascinating. And it's also why I think working with someone who has spent years actually looking at diamonds, rather than simply comparing their specifications, can make such an enormous difference!