这个颜色不对。(Zhè ge yán sè bú duì.)
这个颜色才对。(Zhè ge yán sè cái duì.)
The first sentence clearly means "This color is incorrect." The second sentence seems to then mean "This color is correct." What is the significance of 才? Is it being used for emphasis? Would a more accurate English translation be "this color IS correct" with us emphasizing it with our voice? Would it also be ok to say
这个颜色对。(Zhè ge yán sè duì.)
where we omit the emphasis?