A comma is generally used to separate two or more adjectives, adverbs, or phrases that modify the same word or phrase.

• She spoke in a calm, reflective manner.
• They set to their work again grimly, intently.
  

The comma is often omitted when the adjectives are short. one long thin strand

• a small white stone
• little nervous giggles
• skinny young waiters
• in this harsh new light

The comma is generally omitted where it is ambiguous whether the last modifier and the noun—or two of the modifiers—constitute a unit.

• the story's stark dramatic power
• a pink stucco nightclub
  

In some writing, especially works of fiction, commas may be omitted from most series of coordinate modifiers as a matter of style.