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Fish Scales: The Secret to Shimmer

Updated: Apr 7, 2021

Guanine crystals are a common ingredient used to make shimmery make-up and they come from fish! Here is all you need to know about guanine crystals as well as some shimmer options for vegans to sparkle.

Enjoy this read and, as always, click the numbers in square brackets to check out all the references!

What are Guanine Crystals?

Little crystals made from fish by-products. You almost certainly have applied them on your face, body, and nails.

Guanine occurs naturally in more than just fish; more specifically you’ll probably recognize it from grade 9 biology class as one of the bases of nucleic acid in double-stranded DNA.

Guanine: it's in your DNA

Why They’re Used

Guanine crystals give that shimmery pearlescent glow to products. They are used commonly in lipstick, eye shadow, foundation, lotion, and nail polish. They are even painted on to fake pearls to give them that iridescent pearl look.

How Guanine Crystals Are Made

They’re made from fish scales and fish swim bladders. A swim bladder is an organ in some fish that’s filled with gas to help them control their buoyancy underwater. The fish parts are commonly sourced from herring and tarpon fish. The scales and bladders are heated to 65-100°C and then suspended in alcohol. The guanine crystals settle to the bottom and then are filtered out. Those crystals are the bright and silvery pearl essence [i]. From here they are added into all sorts of products.

Are They Safe?

Yes. I wasn’t able to find any studies that show negative side effects from using guanine crystals [ii,iii].

Alternative Names You Might See in Ingredients [iv]:


Environmental Impact

Using fish scales and swim bladders in cosmetics means less of the fish is being wasted which is always an environmental win. Unfortunately it’s very hard to find out if the guanine in your product was sourced from responsible fisheries or from trawlers that totally destroy marine ecosystems. It’s tricky to know where to stand on this one!

Vegan Options

Obviously this is not vegan friendly so some alternative ingredients you might want to look for are mica (a mineral that gets ground down into a fine powder) and biodegradable glitter (plant based NOT glitter made from PET which is a micro-plastic). It is very difficult to make a synthetic version of guanine crystals so if you want that glow created in a lab you’ll have to wait a while [v].

Click here to check out EcoStardust if you want to buy some biodegradable glitter!

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