1. Make the currant gelatin: Put currants and sugar in a large saucepan. Bring to a boil. Reduce to a simmer, and cook, stirring occasionally, until currants are very soft, about 10 minutes.
2. Put 1/3 cup cold water into a small bowl; sprinkle with gelatin. Let soften 5 minutes. Add to currant mixture; stir until gelatin has dissolved, about 5 minutes.
3. Pour through a fine sieve into a bowl set in an ice-water bath, gently pressing out liquid with a spoon; discard solids. Remove from water bath, and let stand, stirring occasionally, until cool but not set. Pour 3 to 4 tablespoons currant gelatin into each of twelve 8- to 10-ounce glasses; set remaining currant gelatin aside. Refrigerate glasses until gelatin is completely set, about 1 hour.
4. Meanwhile, make the panna cotta: Put 1/3 cup cold water into a small bowl; sprinkle with gelatin. Let soften 5 minutes.
5. Put milk, cream, and sugar into a medium saucepan; bring almost to a boil. Reduce to a simmer. Add gelatin mixture, and stir until gelatin has dissolved, about 5 minutes. Pour through a fine sieve into a bowl set in an ice-water bath. Remove from water bath; let stand, stirring occasionally, until cool but not set.
6. Spoon 3 to 4 tablespoons panna cotta over currant gelatin in each glass; set remaining panna cotta aside. Refrigerate glasses until panna cotta is set, about 1 hour. Repeat with another layer of currant gelatin and panna cotta. If either mixture becomes too firm, set over a pot of simmering water until softened.
7. To serve, top each parfait with blueberries and currants, dividing evenly.

Yield: 12 servings