* Shimmer: Mica and other similar materials reflect light, creating a shimmering effect.
* Sparkle: Glitter adds a more dramatic, sparkly look.
* Textured finish: Some polishes use larger, more noticeable particles to create a sandy, bumpy, or other textured effect.
So, it's not about function in the same way that beads might be used in other applications; it's purely for cosmetic enhancement and to create a specific visual appeal.