The thing about jam sugar is that it supposedly dissolves quicker, due to having slighly larger crystals. They also reckon it leaves less of the scum on the top of the mixture so saves you some skimming.

The other thing to watch is that some jam sugar contains added pectin, so look carefully at the package. Some fruits set well by themselves, and you really don't need extra pectin - you could find yourself with jam set like concrete. If it is a fruit like strawberries which are hard to set, you can buy pectin on its own -Certo is one brand name. I have always used bog standard granulated and since I mostly made blackberry and apple, never used anything else. Apples are a great source of pectin.

Good luck with whatever you are hoping to attempt.

When I first started making jam (my first batch was strawberries) it set perfectly with just granulated sugar & lemon juice - which must have just been beginners luck because almost every batch after that I struggled to get a set.

I then tried jam sugar and it worked fine and to be honest I couldn't tell any difference in the taste but I am prepared to be convinced by others who are more experienced than me that it does make a difference.

So I gave up on the jam sugar because everwhere I looked I saw the same comments about it not being necessary and effecting taste etc. Now if I'm desperate I will use a little Certo or powdered pectin (recently rhubarb jam needed it).

Certo doesn't give very helpful advice about amounts to use - on the bottle it just assumes you will be using all the bottle, so what I do is add about 1 tablespoon and then do the saucer test. It has never failed so far doing it this way but then I don't believe in making huge batches of jam in one go. I suppose that amount of pectin would be for about 2 - 3lbs fruit.

I'm just about to have a go at making my own pectin from cooking apples - this could be the way to go for you as well if you plan on making lots of jam (which it sounds like).

Good luck and let us know how you get on. Everyone so helpful on here and I have asked loads of questions