A writing exercise utilizing synesthesia
Synesthesia is when a sense is described with a description usually applied to another sense. As in, saying something smells black. Looks cold or smells hot. It is a sort of confusion/melding of senses that can make for a very poignant turn of phrase. In Keats’ Ode to a Nightingale” we get a sound made by a color “In some melodious plot / Of beechen green”
So give it a shot. Perhaps use the idea of a black rose to focus your thoughts. It is a color of flower invented for its symbolism, as black roses don’t exist in nature. Merely very, very deep reds. Yet it has become a prevalent, concept, at very least. Here’s a little more information about the idea of a black rose.