​Sub ResetCitationColours()

    Dim fld As Field

    Application.ScreenUpdating = False

    ' Loop through all fields
    For Each fld In ActiveDocument.Fields
        ' Reset the visible text of the field to black
        fld.result.Font.Color = wdColorBlack
    Next fld

    Application.ScreenUpdating = True

    MsgBox "All citation colours have been reset to black.", _
           vbInformation, "Citation Colour Cleanup Complete"

End Sub