The sign in the market pointed out that only the skin of the black watermelon was black, and that it was red inside. Good point. Last summer, black watermelons were in the news when a coveted densuke melon, grown only in Hokkaido at the northern tip of Japan, sold for the equivalent of $6100. Mine was 49 cents a pound, making it about $5, but I have some suspicion it differed in other ways as well.