Hi jeannkits,
I think you are wise to be careful.
I don't know much about Mikimoto, but their website says this (I bolded the relevant text):
[FONT=Avenir LT W01_85 Heavy]
"What is the Mikimoto trademark? How do I know that my pearl jewelry is Mikimoto?[/FONT]
[FONT=Avenir LT W02_55 Roman]You can always identify Mikimoto jewelry by our trademark, which is either the outline of an oyster or the Mikimoto name engraved on every jewel. This engraved mark can be found in the following locations:[/FONT]
- Necklaces and bracelets: back of clasp. They are also fitted with a signature M charm. As the clasp is the only place in a strand or bracelet where the Mikimoto trademark is engraved, it is not possible to appraise a strand or a bracelet as genuine Mikimoto without it.
- Earrings: on post, earring nuts or back of earrings
- Rings: inside the shank
- Pendants: on the back of the bail
- Brooches: on the underside of the brooch"
http://www.mikimotoamerica.com/faq