The darker lines and multi colored patterns in Spalted Maple are the result of certain airborn white-rot decay fungi growing in wood. Many woods can become spalted, some are more decorative than others. Once the wood is dry the process is stabilized and will not continue. Care is taken to be sure the decay is not so far advanced as to effect the integrity of the wood.
This particular Rakusu Ring is slightly larger - 70mm - Rinzai sized.