I just saw your question about Sakata Pearl Company. I don't really know much about it but I have some information that might help. My in-laws lived in Japan during that late 50's and early 60's. My father-in-law had a pair of pearl cuff links and a tie pin that was bought from the Sakata Pearl Company, Ltd. I stil have the certificate of guarantee from the company. I'm sure they were bought in Japan. The address listed on the certificate was:
#7 2-chome Kyobashi Chuo-ku Tokyo
tel (28) 9280. 9025. (56) 1790. 7322. I hope this tidbit will help. I was looking up the company myself when I came across your posting on this forum page.