The Riemann correlator characterizes in a gauge invariant way the quantum metric fluctuations around de Sitter spacetime including loop corrections from matter fields. Selecting a de Sitter invariant vacuum in the spatially flat section we derive the Riemann correlator and express it in a manisfestly de Sitter invariant form. Its behavior for sub and super horizon scales is discussed in detail for massless conformally coupled fields. As a limit we also obtain the correlators in a Minkowski background.