If the silver clasp is the original Miki clasp, Wendy is correct! I didn't realize Mikimoto used silver for clasps.
I will say this, however: if you are going to wear them and just don't like the clasp, change it to something you want to wear, but keep the original clasp so you can have it restrung with the original if you decide to sell it someday. Jewelry is meant to be worn and resale value is not the only consideration.