The phrase "fine gradations" refers to very small or precise steps or levels. It means there are many slight variations or distinctions between different points or levels. Full definition
But Honor's flagship began to falter when I compared it to Sony's HDR - enabled handset, which could better illustrate fine gradations in contrast between the lightest and darkest parts of the scene. (tomsguide.com)
The Cloud paintings here on view are large canvases painted in fine gradations of sky blue. (curamagazine.com)
«Why, if species have descended from other species by insensibly fine gradations, (why) do we not everywhere see innumerable transitional forms?» (religion.blogs.cnn.com)