The antonyms for the phrase "more twenty-four-carat" could include words such as fake, counterfeit, cheap, or phony. These words connote the opposite meaning of something being genuine or of high quality, indicating that the item or entity in question is not authentic or valuable. Other antonyms might include words like flawed, blemished, or subpar, all of which suggest that something is imperfect or of low quality. Ultimately, the antonyms for "more twenty-four-carat" are words that convey the opposite of something that is genuine, valuable, and high-quality, instead suggesting poor workmanship or a lack of authenticity.