seal (or stamp) of approval
An official statement or indication that something is accepted or regarded favourably: the minister gave his seal of approval to the project...- It didn't get the official stamp of approval again until 1926, when the university senate and principal gave the procession a cautious thumbs-up.
- The big news this week is that the planners have given the official stamp of approval for the new community facility in the fields opposite Marshallstown houses.
- They and the conservation lobby continue to hope that their efforts to preserve the city's heritage will soon get an official stamp of approval.
See parent entry: approval