Mica Particle Size and Effect

The visual effect of mica powder depends heavily on its particle size:

• Very small particles (under 25 microns): Tend to provide a matte or satin finish and can offer some coverage.
• Medium particles (25-100 microns): Give a pearlescent or subtle shimmer effect, creating a glow or highlight.
• Large particles (over 100 microns): Result in a glittery or sparkling effect.

For your goal of adding a dewy, pearlescent glow like a highlighter to a serum without it looking like large glitter flakes, you should choose a mica with a medium particle size, typically in the range of 25-100 microns.

The product "Light Gold Pearl Mica (Size A, 30 Micron)" with a particle size of 30 microns falls into this medium range. This size is suitable for creating a pearlescent or subtle shimmer effect, which aligns with your desire for a dewy, glowing look rather than a distinct glittery appearance.

Therefore, a mica with a particle size around 30 microns, like the Light Gold Pearl Mica (Size A, 30 Micron), is likely to give you the subtle, pearlescent sheen you are looking for, suitable for a serum to achieve a dewy finish without being overly glittery.