The production of these wines from Gewurztraminer, Pinot Gris, Riesling or Muscat d'Alsace, requires a rarely achieved conjunction of several factors: an exceptional terroir, old vines, perfectly ripe grapes, and morning mists followed by plenty of sunshine to encourage the development of noble rot (botrytis cinera). The "roasted" grapes are then picked, one by one, in a series of selective harvests, and carefully vinified. The levels of sugar obtained in Alsace for the SGNs ("Séléctions de Grains Nobles") are often higher than those in Sauternes. They can be recognized by their exceptionally rich, ripe, concentrated, complex bouquet. Sumptuous aromas of honey and peaches, underscored by spicy notes, make these the greatest dessert wines in the world, with a virtually unlimited capacity to age.