I recently found out that MIKIMOTO stopped putting his trade mark on his products after WW2.
Clasp by: Glitter gal
Or perhaps they weren't stamping then with their logo? Hard to say, could also be that the giver gave them in a mikimoto box without the pearls being mikimoto, I don't believe the value will change, if they are high quality akoya they would be graded and valued as such
30'" MIKIMOTO NECKLACE by: Robert Picciano
This strand of pearls was given to me for my wife in a necklace MIKIMOTO box in 1952 by MR.TOYOTA IN TOKYO, JAPAN. The box was lost. I did have it restrung in 1956, maybe someone made a switch. BOB
Valued Accordingly by:
I am a little confused. How do you know that they are Mikimoto pearls? Is there a clam shell design on the clasp with an "M"? If not then there is no way to discern if they are in fact Mikimoto pearls. Pearls without the signature Mikimoto clasp will be valued accordingly. I don't know if this is much help.
Akoya by: Glitter gal
Not all pearls from Japan are mikimoto, mikimoto is a brand name, if they are mikimoto more than likely the clasp would be stamped, unless the clasp was changed over the years