I've been thinking for some time on this and I am almost nearly dead certain of this.
There is no Blue-toned or colored Nepenthes.
Am I wrong for coming to this conclusion? Do any of you know of or own a species of Nepenthes that produces a blue tone in the pitchers or in the leaves? I cannot think of a single one. Yet, I can think of one for every other color. Strange, is it now?