Stem the grapes and chill thoroughly.
One half hour before serving arrange 1/3 cup. grapes in each sherbet glass.
Combine the orange juice and lime juice and sweeten.
Stir well and pour over the grapes, allowing about 1/3 cup for each glass.
Chill until ready to serve, then garnish each with a sprig of mint.
If desired, fresh raspberries may be substituted for the seedless grapes.