Sheen, shading, shimmer?

What do the different designations in the ink's product description mean?

Sheen: Sheen is a metallic sheen that is most visible when the paper is held at an angle if you've used an ink with sheen. Sometimes it can be in a different color than the base color of the ink, which makes the ink multicolored. The sheen shows up most on coated paper that doesn't absorb the ink as much, such as Clairefontaine or Midori MD Paper.

Shading: Shading describes how much or little an ink varies in darkness and lightness as you write with it. For example, an ink with high shading has a lot of variation between different areas of the letters when you write. Often light inks have more shading than dark inks.

Shimmer: A shimmer ink has glitter or shimmer particles in it that make the ink sparkle. Ink with shimmer can sometimes clog your fountain pen and make it more difficult to clean. An ink with finer shimmer particles minimize the risk of clogging. Feel free to use shimmer ink in pens that are easy to clean, or with a glass pen / dip pen that can simply be rinsed or wiped off.

Be sure to shake a bottle of ink that has shimmer particles in it before using it, otherwise all the glitter will collect at the bottom of the bottle.