What is Masagonie in Japanese Katana terminology?

"""Masagonie"" (真砂沸) refers to a state where the particles of ""Nie"" (沸) - the pattern formed on the blade of a Japanese sword during the tempering process - are mixed in both large and small sizes. This is likened to the fine sand that makes up a sandy beach, which is called ""Masago"" in Japanese, hence the expression. Additionally, the state where Nie particles are lined up is referred to as ""Sunanagashi"" (砂流し).

This term reflects the intricate patterns that can be formed on the blade of a Japanese sword during the tempering process. The mixture of large and small Nie particles creates a unique texture that is likened to the fine sand of a beach. The term ""Sunanagashi"" further highlights the diversity of patterns that can be achieved through the tempering process. These patterns not only enhance the aesthetic appeal of the sword but also attest to the skill and craftsmanship of the swordsmith."