Answer: I would contend that the right answer is irony.
Explanation: Just to elaborate a little on this answer, it can be added that these lines belong to Shakespeare's famous "Sonnet 130," which is a parody—a close imitation of the style of another work or author for ridiculing or mocking—of a traditional love sonnet, as exemplified by Petrarch. Like Petrarch, and those that imitated him, Shakespeare compares her mistress's features to beautiful and perfect objects (the sun, the coral, the snow), but just to contend that she is not nearly as beautiful as those things. His is an extreme form of verbal irony, who makes fun of and offends an actual person by means of a scathing mockery, so it is possible to argue that he is using sarcasm—from the Greek sarkasmós.