By Melissa Pierson
June 09, 1995 at 04:00 AM EDT

There are two styles of casting and costuming in period dramas: a group of misshapen character actors in tatters, or an equally unlikely prevalence of models aswoon in silk. Since Queen Margot is a French film — about the Parisian court during the 16th-century religious wars — it’s the latter. Indeed, ”How very French!” one thinks as the impossibly gorgeous Isabelle Adjani strikes poses amid rivers of gore, scenes of decadent sex and Renaissance spectacle, and the aforementioned silks. French, too, is the movie’s profound belief in its own seriousness (it’s 2 1/2 hours long). But like a lavish gateau, no matter how sweet, it’s only dessert. B-