Feng Shui is not my forte, however I can answer this question.
Rose is generally a red, like a rosè, the wine red by that name. It's an English adaptation of the word rosè.
If you want to work at enhancing your visualisation have a look at the Genius Code Course it has the perfect exercises.
That said, when it comes to doing exercises like the tube of go with all your senses as best you can. If you cannot see the colour with your minds eye, just get a sense of it, what it feels like, that colour over there. And your auditory sense, remember that sounds carry vibration too, so saying, hearing the colour resonates at that vibration, that's why it's okay just to sense it.
Alex