The above is official Airbus material.
All altitude changes must be announced with the appropriate colour, i.e. FL100 blue or magenta. If “Alt blue” was already announced earlier on during an altitude change there is no need to repeat every time (e.g. in a continuous climb or descent) . If “Alt blue” was not there, e.g. when leaving cruise FL, the new FL will be announced with the colour and “Alt blue.”
For go around altitude preparation there is no colour announced.