HOW TO: Check Jam Setting Point

Achieving the right set does carry a certain knack to it. You could try using a jam thermometer but personally I find it a lot easier using a method that my maternal Grandma showed me. 

Before you start to make the jam, put a plate in the fridge. When it's cold you then drizzle some warm jam on to it and return the plate to the fridge to cool for approximately two minutes. You can tell that it has set when you run your finger through it leaving a crinkly track mark. If after two minutes the cooled jam is too runny, continue to boil the jam, testing it every few minutes until you have the right set.