The M mark you see is the Mikimoto signature, the makers mark, that appears inside an actual clam shell, type of shield.
Mr Mikimoto was something of a marketing genius. Not only did he stamp his own name onto pearls but he stamped the oyster shell into shields as well!
Mikimoto pearls are the best name in cultured pearls. The finest quality of cultured pearls. Also Mikimoto pearls are the industry benchmark when it comes to pearl grading.
More information about Mikimoto pearls can be found here: Mikimoto Pearls Information about caring for Pearls can be found here: Caring for Pearls
