1. Choose fine sweet grapes.
2. Remove the stalks from the grapes, retaining only the best fruit.  Put through a mouli or fruit press to extract the juice; there should be about 2ltr.  Strain through a fine sieve to remove the pulp.  Leaving the pulp in will give you a more grainy textured jelly, and, while in no way changing the flavour, will make for a less pleasing result.  Pour into a jam pan set over a medium heat.
3. When the jelly has come to the boil, keep cooking at small bubble stage for about 45 mins, stirring every 10 mins with a wooden spoon.
4. The jelly is cooked when a drop dripped onto a cold plate sets immediately.(110°C).

See Grape jelly tart recipe