Considered a wood of beauty, burl walnut boasts a striking grain color and pattern. It varies in color from swirls of chocolate brown to purplish black with occasional purple streaks. Its exotic figure and color make burl walnut a highly sought after choice for furniture makers, artists, and wood sculptors. Trees are like oysters, not every oyster produces a pearl, and not every tree produces a burl. American Black Walnut trees, one of the largest hardwood trees in North America, are known for imposing size and strength.