For the apricot-lavender jam, first wash the jars and lids hot and boil them. Turn them upside down and let them dry. Put them directly in the place where they are to be filled (tray with cloth).
Sort out the lavender flowers, but do not wash them. Roll the lemon with the palm of your hand over the kitchen counter (gives more juice), cut in half and squeeze.
Prepare the apricots (wash, blanch, skin, halve and pit) and cut into small pieces. Mix apricots, lemon juice, jelling sugar and lavender in a wide, high pot.
Cover and allow to infuse for at least 4 hours. Stir occasionally. Then boil until bubbly, about 4 minutes (follow directions on sugar package). Stir constantly so that the apricot-lavender jam does not burn.
Skim the apricot-lavender jam if necessary. Make a jelly test. For the jelly test, pour some jam onto a cold porcelain plate. If the jam gels, pour into jars.
Pour the apricot-lavender 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.