Yes, lavender does dilute red and black. When lavender is applied to buff, it would produce a lighter buff, almost cream colored plumage. There shouldn't be any grayish color if buff is consistent throughout. The gray is produced by diluting black. When we were working on our lavender birds, we did get various shades of lavender dilution, from very dark to very light grays, but no one seemed to know what caused that. There is really not much research on lavender, so most everything is trial and error from my understanding.