Circle with Three-Tiered Diamonds Adult Apron

Maru ni Sangai-bishi is a crest with three diamonds stacked inside a circle. According to 'Monsho', a 1925 book on crests by Takeda Masami, a former uwagaki artist, a diamond is formed by combining two equilateral triangles. However, the book notes that using this geometric diamond shape directly in a crest can make it appear too short and weak. It then explains an alternative method for designing diamonds in crests. The Matsukawabishi and Sangai-bishi crests are actually based on the geometric diamond shape rather than the crest diamond shape. (Reference: 'Hanetsuki no Hanashi: Uwageshi ga Kataru Monsho no Bi' by Awazaka Tsumao)