Hardwood
Walnut
The accent wood. Rich, dark, and warm without stain. Best used where you will touch it: shelves, benches, a bar top.
Walnut is what people point at. The floating shelves over the coffee bar and the window bench on this site are walnut, and in both cases the wood is the whole design. It comes out of the mill a deep brown with purple and gold in the grain, and it needs no stain, only a clear oil or matte finish.
It is softer than oak, so it is not a great stair tread or a kitchen floor. It is a superb shelf, bench, countertop for a bar or desk, mantel, or door. Live-edge slabs, where the natural edge of the tree is left on one side, are where walnut earns its price.
In dry air walnut is moderately stable. Slabs are the exception: a wide live-edge slab will move seasonally no matter what, so Luke flattens them after acclimating, uses hidden steel supports that allow for movement, and finishes all faces.
Walnut lightens slightly with sun over years, which most owners like. Keep it out of direct south-facing light if you want it to stay dark.
Care
Oil finishes can be refreshed with a wipe-on coat every few years. Avoid silicone polishes. A scratch in walnut is usually fixable in place.