Cobalt is known for its deep blue colour, read as depth, calm and intensity of feeling. It can stand for a vivid mood that colours the whole dream.
Where in your waking life have you met something like this lately?
My Cosmic Code has a private dream journal. Write a dream down and the app picks out the symbols in it, shows what dream books say about them and, over time, which words recur across your entries. The journal is stored on your device only.