Soak the gelatine in a dish of cold water for about 5 minutes. It will go from brittle to slippery. Place a few grape halves into each of the cups/containers. Now place the grape juice in a saucepan (or in a microwave) with the sugar and heat gently until the sugar is dissolved. Turn off the heat. The mixture should be tepid, not hot. Remove the gelatine from the water and place in the saucepan. Stir gently until it's dissolved. Now pour in about 1/3 of the sparkling grape juice into the saucepan. Pour the remaining sparkling grape juice into each of the cups/containers. Pour the gelatine mixture on top. Place in the fridge and leave to set.
You can substitute any juice for the grape juice as long as you keep the proportions the same. Most fruit will work well in this dessert with the exception of pineapple and kiwis which may stop the jelly from setting.