Why Does Moissanite Sparkle So Much? Fire, Brilliance and Scintillation

Moissanite sparkles more than almost any other gemstone. It returns a lot of white light, and it splits light into more rainbow color than diamond. That combination is why people notice it from across a room, and why some people love it while others prefer diamond's calmer, whiter sparkle. Here is the science in plain words, and what changes how much your stone sparkles.

Sparkle Is Three Different Things

• Brilliance is the white light a stone sends back to your eye.
• Fire is the flashes of rainbow color, made when white light splits into its colors.
• Scintillation is the play of bright and dark flashes you see when the stone, the light or your eye moves.

Moissanite is strong in all three, and especially in fire.

Brilliance: A Higher Refractive Index

A gem's refractive index (RI) measures how much it bends light. Moissanite's RI is about 2.65 to 2.69, higher than diamond's 2.42. The higher the RI, the more light gets trapped inside and bounced back out through the top instead of leaking out the bottom. For the gem-minded: light that meets an inner facet at more than about 22 degrees from straight-on is reflected back inside moissanite, compared with about 24 degrees for diamond, so a well-cut moissanite returns a lot of light.

Fire: More than Twice Diamond's Dispersion

Dispersion measures how strongly a gem separates white light into colors, like a prism. Moissanite's dispersion is 0.104, more than twice diamond's 0.044. That is why a moissanite flashes more red, orange, green and blue, most of all in sunlight and under spotlights. Some people call the effect in large stones a "disco ball" look; others simply call it the best thing about moissanite.

See how these stones compare overall in best diamond alternatives.

Scintillation: The Cut and the Facets

Scintillation comes from the facets. Many small facets, as in a round brilliant or a Portuguese cut, give lots of quick, fine flashes. Larger facets, as in old European or emerald cuts, give fewer but bolder flashes. Our moissanite cut guide ranks every shape, and our antique cut guide covers the vintage looks.

What Changes How Much It Sparkles

• Lighting. Sunlight and spotlights bring out fire. Soft, even office light shows more white brilliance. Candlelight makes antique cuts glow.
• Size. Bigger stones have bigger facets, so the fire is easier to see.
• Cut quality. A stone cut too shallow or too deep lets light leak out, leaving a glassy "window" or dark areas.
• Cleanliness. A thin film of lotion or soap on the back of the stone dulls it more than anything else. See how to clean moissanite.
• The setting. Slim prongs and an open setting let more light in. A halo adds extra sparkle around the centre stone.
• Color. Colorless stones show the most rainbow fire; colored moissanite shows its body color with flashes of fire on top.

Quick Answers

Does moissanite sparkle more than diamond?

It shows more fire and is very bright, so most people would say yes. Diamond's sparkle is whiter and calmer, which some people prefer.

Why does my moissanite show rainbows?

That is its high dispersion, or fire. It is a property of the stone, not a flaw, and it is strongest in direct sunlight.

Does moissanite lose its sparkle over time?

No. The stone does not change; if it looks dull, it needs cleaning. See does moissanite get cloudy?

Which moissanite cut sparkles the most?

Brilliant cuts with many facets: round, radiant, crushed ice cushion and Portuguese.

See it for yourself in our moissanite engagement rings, or start with what is moissanite?