The heat is on in the luxury businessThe Baselworld watch and jewelry fair was on fire. Literally.? On three successive nights of the show—held March 24–31 in Basel, ­Switzerland—flames shot through the rooftop of the Hall of Elements as Swiss watch brand Breitling commandeered the space for one of its legendarily risqué pyrotechnic parties.As a metaphor, the blaze made its point. Business at the luxury show was brisk; some might even have called it sizzling. Although the mood did not recall the carefree decadence of 2007, it marked such an improvement over the darkest days of the crisis that most exhibitors declared a de facto recovery. The exuberance was not, however, reflected in the newest watches. Conceived a few years ago at the peak of the recession, the models unveiled in Basel were remarkably sober?: Classic, thin, and unadorned styles reminiscent of timepieces from the