Gorgeous, Bree. It really does look huge with your hand in there, but 13cm. is about 5in. so a nice big flower but not quite as enormous as the picture looks.
Ursula, thanks. Of course Big Jim is a B. nodosa sport, and I shouldn't be lazy about those long names. Does 4N mean the same as "tetraploid" which term they use for things like daylily hybrids?
Jim, my daughter remembered she bought it from Florida SunCoast Orchids in Myakka City. They still have it on their website.