This weekend I was looking again at an appendix in Bert Fridlund's book Spaghetti Westerns: A Thematic Analysis in which he lists the top grossing Italian Westerns from 1964-1975 (He basically lists the top 47 films).
Gemma did not make it into the top 10. Those spots were taken by either Leone films, Trinity films and their spawn, or Red Sun.
The highest Gemma achieved was 13th with Day of Anger/1966.
But I noticed some other things that made a (perhaps) useful comparison between him and Tomas Milian and Franco Nero.
None of Milian's films or Nero's films made it into the top 10 either. But...ALL of Gemma's films made during this period were top grossing films. Not so with Milian or Nero.
Here is a list of Gemma's films from 1965-1974 along with their rankings:
13th Day of Anger/67
15th The White, the Yellow & the Black/74
19th One Silver Dollar/65
20th Adios Gringo/65
25th A Pistol for Ringo/65
26th Return of Ringo/65
27th Fort Yuma Gold/66
28th The Price of Power/69
30th Arizona Colt/66
32nd Alive or Preferably Dead/69
37th And For a Roof a Sky Full of Stars/68
38th Ben & Charlie/72
43rd Long Days of Vengeance/67
So, ALL 14 of Gemma's films made during this period made good money.
Nero had only 6 films in the top 47 & Milian had only 7 films.
But here's (to me) the kicker: in MOST of Gemma's 14 films, he was the ONLY major star.
He co-starred with Van Cleef in Day of Anger & with Eli Wallach and Tomas Milian in The White, The Yellow & The Black (Tomas Milian should have retired immediately after making this film and spent the rest of his life seeking out and destroying every known print). Gemma also co-starred with George Eastman in Ben & Charlie and with Nino Benvenuti in Alive or Preferably Dead but they were not, I believe, on par with the other actors mentioned here.
So...Gemma, BY HIMSELF, propelled 10 or more of his films into the top grossers. Nero shared billing with top co-stars in 2 of his 6 top grossing films and Milian had heavyweight co-stars in 4 of his 7 top grossing films.
Don't know if my analysis is valid but I found this interesting and thought others might too.