This is Bob(Colorado, USA) a.k.a.
                         "Cool 1"   and this is 

Ingredients

4C washed, drained blueberries,
4C sugar
1 tsp. lemon juice

Method

1) Combine berries, sugar & lemon juice in large pot (4qt)

2) Over low heat, stir berries & sugar until liquid starts to form

3) Turn heat all the way up and cook until rolling-boil stage

4) Cook at rolling-boil stage until a teaspoon of jam dropped on a plate solidifies to the stage you like it

5) At that point turn heat off. Skim off any foam and ladle into hot sterilized jars (1/2pts.) Water bath for 15 minutes
(6 to 7 jars)
 

• At this altitude here, 7.000ft, it needs to cook at rolling-boil for 10 to 15 minutes, but at sea level it would probably be about half that time