Score the apricots crosswise, place in boiling water until the skin can be peeled off. Quench in cold water, peel, halve and stone.
Open 10 apricot stones with a nutcracker, boil the kernels in a small saucepan with water for 1 minute, drain and peel off the skin. Finely chop or grind the kernels.
Cut the apricots into small pieces and mix with the sugar. Wash 1 lemon with hot water, rub the peel, squeeze both lemons. Add the juice, zest and kernels to the apricots and let steep for 12 hours. If you don`t want any pieces of fruit in the jam, you can puree them now.
Bring the apricots with the leaked juice to the boil in a large saucepan, stirring until everything is bubbly. Cook the preserving sugar according to the package insert and pour into hot glasses immediately. Turn this 10 minutes upside down.