16 C.F.R. § 23.20
Misuse of the word “pearl.”
(a) It is unfair or deceptive to use the unqualified word “pearl” or any other word or phrase of like meaning to describe, identify, or refer to any object or product that is not in fact a pearl, as defined in § 23.19(a).
(b) It is unfair or deceptive to use the word “pearl” to describe, identify, or refer to a cultured pearl unless it is immediately preceded, with equal conspicuousness, by the word “cultured” or “cultivated,” or by some other word or phrase of like meaning, so as to indicate definitely and clearly that the product is not a pearl.
(c) It is unfair or deceptive to use the word “pearl” to describe, identify, or refer to an imitation pearl unless it is immediately preceded, with equal conspicuousness, by the word “artificial,” “imitation,” or “simulated,” or by some other word or phrase of like meaning, so as to indicate definitely and clearly that the product is not a pearl.
(d) It is unfair or deceptive to use the terms “faux pearl,” “fashion pearl,” “Mother of Pearl,” or any other such term to describe or qualify an imitation pearl product unless it is immediately preceded, with equal conspicuousness, by the word “artificial,” “imitation,” or “simulated,” or by some other word or phrase of like meaning, so as to indicate definitely and clearly that the product is not a pearl.