There are a few ways that you can tell if wood is walnut. One way is to look at the color of the wood. Walnut typically has a darker brown color than other types of wood. Another way to tell if wood is walnut is to look at the grain pattern. Walnut typically has a straight grain pattern, while other types of wood may have a more random grain pattern. Finally, you can usually tell if wood is walnut by its weight. Walnut is a heavier type of wood, so it will feel denser than other types of wood.