When you encounter someone or something with great potential but no polish, you might refer to it as a "diamond in the rough." However, this popular phrase has several synonyms that can add nuance and variety to your writing. For instance, you might say that someone is a "rough-hewn gem," a "hidden treasure waiting to be unearthed," or a "raw talent in need of refinement." Other options include "undiscovered gem," "unrefined jewel," and "uncut diamond." By using different synonyms for "diamond in the rough," you can express similar ideas with greater precision and creativity.