Lorraine, Mikimoto marks are distinctive and so are their clasps. They also have different lines of varying qualities. Showing a photo to a Mikimoto representative should answer your question. They will be able to identify them for you. My experiences with contacting the Mikimoto company have always been favorable, so don't hesitate to try. I was thrilled to meet the current president of Mikimoto last March in Dubai...he wasn't at all scary, but very friendly. Unfortunately the name Mikimoto is used often fraudulently or even simply mistakenly, as in the Philippines, where a common name for akoya pearls is "Mikimoto"....very strange. It took me awhile to figure out what they were trying to convey.