The gold wreath due to be auctioned at Bonhams (lot 240) next week is discussed on "Archaeology Matters". There is a link to a report in the Greek press (N. Kontrarou-Rassia, "Στο σφυρί μοναδικά και πανάκριβα αρχαία", Eleutherotypia, April 9, 2010). It appears that Greek archaeologists have contacted Bonhams asking for further information about the wreath and requesting additional photographs.
The first documented appearance of the wreath was at Sotheby's in London (July 11, 1988, lot 83). However it is also stated that the wreath resided in an unspecified private Swiss collection; the date of acquisition is uncertain ("between the 1930s-60s"). This sounds like one of the "interesting provenances" that was highlighted in the press release issued by Bonhams.