Here’s the 2×4 ring which resembles wood with intricate wood grain detailing. There is a diamond in the ring – cleverly working as the knot in a tree. You can get this as a solid 14k gold ring, or in gold vermeil or oxidized sterling silver. You can also get it made without the diamond, if you just want it to be simpler.
This ring is from Digby & Iona, from their “The Wood” Collection.