for entry in eachentrysaved(finenv.Region()) do
   -- Only process 2-note chords
   if (entry.Count ~= 2) then goto continue end
   -- Only process (enharmonically) perfect 4ths
   local highestnote = entry:CalcHighestNote(nil)
   local lowestnote = entry:CalcLowestNote(nil)
   local mididiff = highestnote:CalcMIDIKey() - lowestnote:CalcMIDIKey()
   if mididiff ~= 5 then goto continue end
   -- Create a notehead modification object
   local notehead = finale.FCNoteheadMod()
   -- Remove any old notehead data for this entry
   notehead:EraseAt(lowestnote)
   notehead:EraseAt(highestnote)
   -- Create a diamond character that is 110% of the default size
   notehead.CustomChar = 79
   notehead.Resize = 110
   notehead:SaveAt(highestnote)
   -- Jump label here:
   ::continue::
end