If you've ever wondered what makes your lipstick shimmer, you might be surprised to learn that the cosmetics industry once relied on an unexpected marine source: fish scales. Specifically, crushed scales from herring were processed to extract a crystalline substance called guanine, which created that coveted pearlescent glow.

But before you toss your entire makeup collection, here's the real story about what's actually in your lipstick today.

The Science Behind the Shimmer

Guanine is a naturally occurring compound found in the scales of certain fish. When finely processed, these crystals have remarkable light-reflecting properties that create an iridescent, pearly effect. Cosmetics manufacturers discovered this made for gorgeous shimmery finishes in lipsticks, nail polishes, eyeshadows, and highlighters.

The scales were typically sourced from herring and other fish, crushed down, and refined into what was sometimes labeled as "pearl essence" or "natural pearl" on ingredient lists. You might also see it listed as "CI 75170" or simply "guanine."

Why Most Modern Lipsticks Are Fish-Free

Here's where the fact becomes outdated: most major lipstick brands have moved away from fish-derived guanine. The cosmetics industry has largely transitioned to synthetic alternatives that replicate the pearlescent effect without raising ethical or sustainability concerns.

Today's shimmery cosmetics typically contain:

Synthetic mica - Lab-created minerals that provide a brighter, cleaner shimmer
Bismuth oxychloride - A synthetic compound with excellent pearlescent properties
Titanium dioxide-coated mica - A common modern alternative
Borosilicate substrates - Exceptionally transparent for unique color effects
Synthetic pearl and aluminum powder - Cost-effective shimmer sources

These alternatives are often cheaper to produce, more sustainable, and easier to source consistently than fish-derived ingredients. Even when guanine is used in cosmetics today, it's typically the synthetically produced version rather than the fish-scale variety.

How to Know What's In Your Lipstick

If you're curious about your specific products, check the ingredient list. Fish-derived guanine would appear as "guanine," "pearl essence," "CI 75170," or sometimes "natural pearl." But finding it in modern formulations is increasingly rare.

The shift away from animal-derived ingredients reflects broader trends in the cosmetics industry toward vegan formulations, ethical sourcing, and synthetic alternatives that perform just as well—or better—than their natural counterparts. The child labor concerns surrounding natural mica mining have also accelerated the move toward synthetic options.

The bottom line? While your grandmother's lipstick might have contained actual fish scales, your current favorite shade almost certainly doesn't. The beauty industry has evolved, and today's shimmer comes from science, not the sea.

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