The evidence presented is not totally convincing that Wolfram took his concept of the Grail from some knowledge of the Corpus Hermeticum (CH), but nevertheless they offer a number of intriguing points, and propose a number of sources for Wolfram which may not be so easy to discount. They are very thorough indeed in offering possible parallels between Parzival and the CH.
   They interpret Wolfram's curious "lapis exillis" as the lodestone, the psaltry stone (exillis = exilis), and point out that the Krater in CH 4 is also likened to the lodestone ("magnetis" in the Greek of the CH), which when beheld by men draws them like iron to a magnet. Interesting, but perhaps only a coincidence. They also provide unprovable proposals regarding Wolfram's Tebit, Flegetanis, and Kyot. They identify Tebit as the Sabian philosopher of the ninth century Thabit b. Qurra originally from Harran, and that the "Book" which in a rather devious way the Harranians used to save themselves from conversion to Islam was in fact the CH. The authors propose that knowledge of the CH in some form translated into Arabic would have come to Wolfram via Kyot, whom they identify with William of Tudela, "Kyot" being Wolfram's transliteration of the Catalan "Guillot" a diminutive of "Guillem". They offer evidence to support this identification. They also suggest that "Flegetanis" might derive from the Arabic al-Falakiyatu or falakiyatun meaning Astronomy/Astronomer, which is the title of an Arabic Hermetic treatise on astrology. But with all the other fanciful names used by Wolfram, it is possible that Wolfram could have picked names such as these to provide an air of authority for his stated sources without having any real knowledge of any earlier works such as Arabic Hermetic texts. The attempt to link "gradale" directly with the Late Latin "kratera" as in Greek "krater" in CH4  is less convincing.

More detail to come.