Seiyei Fine China

The image shows the backstamp of a teapot or cup, identified as Seiyei Fine China (indicated by the kanji '清秀' within the diamond mark). Seiyei & Co. was a prominent manufacturer and exporter of Japanese porcelain based in Nagoya, active primarily throughout the mid-20th century.

Historically, the brand catered heavily to the export market, particularly the United States and Europe, during the post-WWII 'Occupied Japan' era and through the 1960s. These pieces are typically identified by their thin-walled 'fine china' quality and traditional Japanese decorative motifs. Today, Seiyei persists largely as a collectible vintage brand, as the original manufacturing entity in Nagoya has evolved or ceased large-scale commercial operations in its original form.