Although I did not use any frets on the cello for my recording, worth of note is the fact that many cellos were fretted, just as viols and lutes. Drawings by Stradivari have come down to us that shows his calculations to fit frets on a neck, before this was modified, alas a common destiny of so many baroque instruments. A fret, by no means limited to being a visual aid for fingers to find their place on the strings, is essentially a sound-mechanism to imitate the resonance of the open string as much as possible.