How does a cushion cut diamond sparkle compared to a round one?

A round brilliant is a math problem solved. A cushion cut is a conversation.

The sparkle difference comes down to facet arrangement. A modern round brilliant has a highly engineered pavilion pattern-eight arrow-like reflections when cut to ideal proportions-designed to bounce light straight back at your eye. It's consistent, predictable, and extremely bright. A cushion cut, especially the ones most people buy today, is a modified brilliant. That means the pavilion facets are split into an extra row, creating a shattered mosaic of light instead of clean arrows. You'll hear people call this "crushed ice." Some love it. Some think it looks chaotic. I've set enough of both to know that it really does change the whole personality of the stone.

Two months ago a client named Elise came in with a specific request: a 1.04 carat cushion, G/VS1, with a simple platinum solitaire. She'd seen photos online and loved the soft, romantic look. I pulled three stones from my dealer. Two were modern cushion modified brilliants; the third was an antique old-mine cut-a true cushion cut from the 1910s, recut slightly but still carrying those chunky, knife-edge facets cut for gaslight. The difference under my scope was immediate. The modern stones threw a thousand tiny pinpricks of light. The old mine cut threw bolder, broader flashes of rainbow fire. Elise stared at them for a solid fifteen minutes, then said, "They don't even look like the same diamond." She was right. They don't.

Cushion cuts, unlike rounds, don't get a GIA cut grade. That means you have to evaluate brilliance with your own eyes. The facet patterns vary wildly between manufacturers. Some cushions are cut so deep that light leaks straight through the bottom and you get a dead, glassy center. Others have a mild bowtie-a dark horizontal band, though less pronounced than in ovals-right across the table. And many contemporary cushions lean heavily into that crushed-ice look, with the extra facets creating a silvery, sleet-like shimmer rather than the defined fire of a round. If you're after maximum light return and that crisp eight-point symmetry, a round brilliant wins every time.

But sparkle isn't just brightness. Fire-the colored flashes-behaves differently in a cushion. A round brilliant launches quick, metallic tongues of color. A cushion, especially an old mine or an antique cushion, releases them slowly, often in larger washes that shift as your hand turns. The facets are larger than on a modern modified cushion, so the colors step out instead of flickering. It's the difference between a camera flash and a fireplace glow. I've had clients who were dead-set on a round brilliant until they saw a well-cut old mine in dim restaurant lighting. Then they switched.

One more thing most jewelers won't tell you: a lot of online cushion photographs are taken under intense LED spots that exaggerate their sparkle. In real office lighting, a crushed-ice cushion can look slightly hazy. It's still a diamond, still hard as anything, but it won't punch light at you like a round does. That's not a flaw. It's a trade-off. My own engagement ring has a .94 carat old mine cut, set in a worn 18k gold band. It's not the brightest stone in the room. I wouldn't trade it.