I reached out to cosmetic chemist Stephen Ko for an ingredient breakdown and the science behind the black-to-pink color change. Turns out, this product contains a very special dye called Red 21 (CI 45380), which is responsible for the color-changing properties in numerous products, including Lipstick Queen's Frog Prince Lipstick and Clinique's cult-fave, looks-fab-on-everyone Almost Lipstick in Black Honey ($18). You can find a variation of this dye listed as Red 27 in Almost Lipstick in Black Honey ($18) and Winky Lux's Flower Balm Jelly Lip Stain ($14).
"Red 21 is yellow, possibly clear, in oil solution. When it interacts with water, it turns red," explained Ko, who added that the blush also contains black iron oxide, which helps give it that velvety black color. "The added pigments can 'tint' it, but [the blush] is not reacting to the specific pH of your skin."
So basically, this blush will look different on every single skin tone, but it ultimately changes into the same shade of pink for everyone. Ko explained that what makes this blush — -and other products like it — feel like such an "intuitive" or "customized" color is the sheerness and buildability of the formulation.
