Place raspberries in a stainless steel or enamel pot and add sugar.

Let sit for a few minutes and then stir to combine.

Bring the jam to a boil over high heat, stirring often. It will foam up and expand, so expect that when you chose the size of the pan you will be using.

If foam forms on the surface, skim it off with a metal spoon or skimmer. Continue to boil, stirring until the mixture reaches the gel point, 102C°/215F°. The jam should be fairly thick.

Remove from heat, stir in lemon juice and let cool.

Place in container and cover top of jam with plastic film to prevent forming a skin and place in refrigerator.