The phrase "reddish blues" can be difficult to describe using single words. One possibility is to turn to synonyms for the colors red and blue, such as scarlet and azure. Other options might include words that describe a mix of the two colors, like purple or lavender. Descriptors like "berry-toned" or "wine-colored" might also help to capture the warm, deep quality of reddish blues. Additionally, words like "ocher" or "rust" could evoke a sense of the earthy warmth that reddish blues can sometimes convey. Ultimately, the best synonyms for this particular phrase will depend on the context and tone of the writing.