Shimmer

Shimmer suspends reflective particles in a base: mica, synthetic fluorphlogopite, or coated borosilicate in the sparkliest formulas. Particle size sets the whole character. Very fine particles read as a smooth glow with no individual points visible, larger ones read as distinct sparkle, and the coarsest are simply glitter. Looking at a swatch under a light rather than in a shadowed aisle is the only reliable way to tell which you are buying.

Placement is the technique. Light lands on the brow bone, the inner corner of the eye, the top of the cheekbone and the center of the lip. Shimmer put there looks intentional. Spread across a whole cheek, it looks like sheen you did not choose. Press it on with a fingertip or a flat brush rather than sweeping. Sweeping scatters particles instead of laying them down, and it produces the fallout that ends up under the eye.

Texture is the weakness. Reflective particles sit on top of whatever the surface is doing, so raised pores, bumps and flaking all become more visible under shimmer rather than less. Safety matters more here than in the other finishes. Only cosmetic grade glitter belongs near the eye. Craft glitter is cut from plastic sheet with edges that can scratch the eye's surface. Nothing loose belongs in the waterline. If a particle gets into your eye and irritation or blurred vision does not clear, an eye doctor should look at it.