Glitters (or glisters) in this case is not a noun but the verb to glitter (or to glister). 'All' is the noun, which is a mass noun that takes the singular form.

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

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. It is also used on optically variable inks.

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