A 1976 monograph:

IMAGE- 'Diamond Theory,' © 1976 by Steven H. Cullinane

A 2012 mixtape cover:

IMAGE- Cover image for a free mixtape, 'Lawrence Class - The Diamond Theory,' that contains images from Steven H. Cullinane's 'Diamond Theory.'

A new "Diamond Theory" image found on the Web
today links my work to the "Stoned Ape Theory"
of human evolution due to Terence McKenna. 

This link is via a picture, apparently copied from deviantart.com,
of two apes contemplating some psychedelic mushrooms.
The picture is titled "Stoned Ape Theory." The mushrooms in
the picture are apparently taken from an image at DrugNet.net:
 

Actually, the mathematical work called "diamond theory"
has nothing whatever to do with psychedelic experiences,
although some of the illustrations may appeal to McKenna fans.