All that glisters is not gold. Nevertheless, what most people say is "glitters." It's the singular, because it's kind of a reverse formation: gold is not all [the only thing that] glitters.

Glitter is commonly used in arts and crafts to color, accessorise and texture items. The small, brightly colored particles often stick to clothing, skin, and furniture, and can be difficult to remove.

glitter (countable and uncountable, plural glitters) A bright, sparkling light; shininess or brilliance.

: to be brilliantly attractive, lavish, or spectacular. also : to be superficially attractive or exciting. glitter.