Identify & info on Yamada Tokyo Earrings

by Jennifer
(New York, NY)

Vintage Yamada Tokyo earrings screw back clip on, signed in a gold oval as shown -acquired in the 80's, but 2nd owner. Very possibly ivory, they have striations (more evident now) & characteristics of elephant ivory not bone, throughout the earring. Very slight yellowing - I'd guess age related. Certain about inlay of rosewood and ebony. But who is he? Approx age of them? Are they rare, fine art? or are they costume? Value today? Are they legal to sell if they are ivory? I've only seen 1 brooch online with the same signature, but minimal info. He/she's an enigma!