These pictures are of smoke released by a burning incense stick. Smoke is grey to the human eye, but with a little post processing in Photoshop or similar editor the underlying colour can be revealed. For the technically minded, change the colour temperature and increase the saturation to see what I mean.
Smoke photography is tricky, not least because it is hard for the camera to focus on the smoke. With practice and a lot of trial and error some interesting results can be produced.
Not all incense sticks are created equal. If you find the type where the incense is bonded to a wooden core two types of smoke are created, one from the incense and one from the core. Being chemically different they give rise to differently coloured smoke. In the first picture below you can clearly see both blue and gold colours. Neat
