I have asked this question now of the seller and with any luck they will answer on the site as well as to me. It looks to me as if they are beaded but I am guessing that the seller probably has been told they are naturals and has no real idea what that means. They seem to just sell all kinds of things and probably don't know the meaning of natural pearls.
I wrote to the seller. An estate jeweler told her so. She pulled the auction. I told her to relist it as cultured pearls. I told her the jeweler should not have said it was natural without a certificate of authenticity from the GIA and that there is a difference between an appraisal and a certificate from a gem lab.
I am sure she is honest, and was just jerked around by a foolish jeweler.
That starting price is totally reasonable and the strand should sell for more than that!