Well done, Sophie! I have no idea how I missed the index entry when I checked the book, but perhaps I only looked in the "Index of Weights" section rather than the general Index which precedes it :spls:
But with the various references and comments we do seem to be getting some variations in names etc! So, for clarification:
Ellie's title for the thread gives "Steltzer", but her initial text shows "Stelzer"
The hand written label on the base of the weight seems to show "Stiltzer" (first vowel "i" not "e", but with the second "t")
The Delaware Valley article linked earlier gives "Steltzer" (with the sectond "t")
The book refers always to "Stelzer" (same as Ellie's initial text)
The book is by Jean Melvin (not Melville). The colour plates in the 1970 Revised Edition are positioned in two sections, after pages 32 and 48, and the Stelzer weights are (in my copy) certainly in the ones after page 48 but on the 17th page of all the colour pages.
Sorry to sound so pedantic but, as the book has no page numbers for any of the pages with colour plates, and no reference numbers for the individual plates (b&w or colour) I found it a bit difficult at first to locate the entry. But in fact even though many (or most?) pages are not numbered, the numbering is sequential through everything, so the colour plate we are talking about is on page 57 of the book.
However, I agree that the weight on the left of the colour plate is in the same style as Ellie's weight - although it is not identical. And it is is possible that the weight pictured in the front of the book (as a b&w image) is the same one as in the Stelzer colour image, but shown at a different angle.