The surface on some of those pearls doesn't look very good, and the luster doesn't seem very good either. I would not have thought them to be Mikimotos if all I saw was the pearls and not the clasp. As KarinK pointed out, people do sell non-Miki pearls with a Miki clasp --and Miki clasps are also counterfeited.
Do look at completed listings on eBay, but realize that a fine quality strand will sell for more than one with lower luster and surface quality.
If she lists it she must be careful to photograph closeup shots of the flaws, to avoid having the pearls returned by a disappointed buyer.