What does a diamond note head mean in a bass part when it’s the only note on the staff?

Question

My amateur orchestra is playing Ravel’s Mother Goose Suite. The bass part has a number of notes with diamond heads. I’m not sure how to interpret them (and neither is our conductor who plays viola). In Viola and Cello diamond notehead notation interpretation the diamond notes are accompanied by regular notes to indicate which note to play and which to touch for a harmonic. This score has regular harmonics:

Then it also has these diamond notes:

It also has diamond notes specifically for basses with five strings (which my section-mate happens to play):

How do we play these?

Answer 1

Diamond example 1: The below comes from Leonardo Lebas, "String Harmonics in Ravel’s Orchestral Works", MMThes (Penn State, 2006), p. 8

Ravel [sometimes] wrote only a diamond-shaped note indicating the pitch where the node producing the desired harmonic is found on the string. These are the cases that cause more confusion because, most of the times, Ravel did not indicate in what string to play the harmonic, as Koechlin stated in his orchestration treatise (p 188, v.1). In theory, there may be more that one interpretation for this string harmonic notation but in fact, the actual sounds are clarified by the harmony or by the orchestral context.

Diamond example 2: The diamond-shaped note heads designate the position in which the harmonic should be played, and the regular note head above is the (harmonic) pitch to be produced. (Based on Leonardo Lebas, "String Harmonics in Ravel’s Orchestral Works", MMThes [Penn State, 2006], p. 8).