In Shakespeare's Sonnet 93, the speaker attributes the distinct quality of being "black" or "stained" to his beloved's face. The sonnet explores the internal turmoil and conflicting emotions experienced by the speaker due to his beloved's unfaithfulness. The use of the term "black" or "stained" suggests that the speaker sees a flaw or darkness within his beloved's appearance, possibly reflecting the emotional pain and betrayal he feels. This dark imagery contrasts with the usual praise and idealization of beauty found in traditional love sonnets, adding complexity to the speaker's emotions and the relationship depicted in the poem.