  We present cross section predictions for the isolated diphoton production in
next-to-next-to-leading order (NNLO) QCD using the computational framework
MATRIX. Both the integrated and the differential fiducial cross sections are
calculated. We found that the arbitrary setup of the isolation procedure
introduces uncertainties with a size comparable to the estimation of the
theoretical uncertainties obtained with the customary variation of the
factorization and renormalization scales. This fact is taken into account in
the final result.
