Rinse the apricots and blanch in boiling water. Remove from the water, cut in half, and remove the stones. Puree half of the apricots with the lemon juice, and finely dice the remaining half. Mix the puree, diced apricots, and jam sugar in a pot.
Cover the mixture and let infuse overnight.
Bring to a boil over high heat. Cook for 4 minutes, then fill the prepared jars to the brim with the jam. Seal tightly and cool completely.