Start of exterior: stucco is really just coloured concrete. So, the house gets a base layer of concrete (which sticks to that layer of wire mesh attached earlier).
The upper part is a smooth finish; the lower section where the rock facing will go is intentionally rough. They let the upper section dry for three or four weeks, so that if it’s going to crack anywhere it will, before they put the final coat on. The colour right now doesn’t matter – it’s just grey concrete – the final coat has the colour in it. (It will be a fairly neutral grey much lighter than what’s there now).