In an article describing the Parke-Bernet auction in which the Peregrina was sold to Richard Burton's lawyer on his behalf, the New York Times writes that "a disappointed bidder was Prince Alfonso de Bourbon Asturias," whose highest bid of $20,000 was not enough to secure the pearl. Rayón and Sampedro, in their book mentioned above, mistakenly identify this bidder as "Alfonso de Borbón Dampierre," who was allegedly trying to obtain the pearl in order to present it to Ena, so that there would no longer be any doubt but that she had the real Peregrina.
I have it on good authority that Dampierre (el Duque de Cádiz) made no such bid, either by telephone or in person. Who then is this "Alfonso de Bourbon Asturias" mentioned in the NY Times? Note the use of "Asturias" which, as you no doubt know, is used to designate the heir to the Spanish throne (i.e, "Prince of Asturias").