For the apricot amaretto jam, first wash the jars and lids hot and boil them. Turn them upside down and let them dry. Place them directly in the place where they are to be filled (tray with cloth).
Cut the lemon in half and squeeze. Prepare the apricots (wash, blanch, skin, halve and pit) and cut into small pieces. Mix apricots, lemon juice and jelling sugar in a wide, high pot. Cover and allow to infuse for at least 4 hours. Stir occasionally.
Then boil until bubbling, about 4 minutes (follow directions on sugar package). Stir constantly so that the apricot-amaretto jam does not burn. Skim the apricot-amaretto jam if necessary. Make a jelly test.
For the jelly test, put some jam on a cold porcelain plate. If the jam gels, pour it into glasses. Pour the apricot-amaretto jam as hot as possible, to the brim, into the prepared jars and seal immediately.
Place the jars upside down on a tray covered with a damp cloth for 6 minutes. Then invert the jars again and let cool on the tray. Store in a dark and cool place.