For the cranberries: Combine the granulated sugar and 1 cup water in a saucepan, and bring to a boil. Cook until the sugar is dissolved. Add the cranberries and weight with a plate to submerge them in the liquid. Cover the pot and refrigerate for at least 8 hours and up to 48 hours.
Drain the cranberries, reserving the syrup. (Yields about 1 1/2 cups syrup; store leftover syrup in the refrigerator in an airtight container for up to 1 month.)
Put the superfine sugar on a baking sheet, and toss the cranberries in the sugar. Refrigerate the cranberries, uncovered, for 1 hour, then toss again in the sugar. Refrigerate in an airtight container. (Makes about 2 cups.)
For the margarita: In a cocktail shaker, muddle the lime and orange zests with the cranberries, 1/4 cup of the cranberry syrup, and the sugar.
Add the tequila, orange juice, lime juice and orange liqueur; stir until combined. Fill 4 glasses with ice cubes, and strain some of the margarita mixture over each. Garnish each glass with 6 sugared cranberries.