Semillon is one of the unheralded whites in the world of wine. It plays a key role in white Bordeaux and in the dessert wine Sauternes, and it makes a great value white from Washington State. Semillon is also the grape responsible for ''Hunter Riesling'' or ''Honey Hunters,'' one of the most interesting of Australia's wines. For a low-acid wine, Semillon takes to bottle age surprisingly well, and it's often inexpensive enough to make laying some down for five years or so very easy. In Bordeaux Semillon is used to fill out the leaner and higher acid Sauvignon Blanc, and the two complement each other very nicely. Semillon is often a brilliant gold wine with a soft, full, and sometimes even oily texture, and often shows a scent of figs. It can be made dry or sweet.