Remove the seeds from the plums and cut them in half. Mix orange juice with agar-agar, blend with the plums in a hand mixer. Stir through cinnamon, blossom honey, ground cloves with the fruit puree, place in a high saucepan, bring to a boil, bubble for 2 min. Immediately fill into prepared jars, seal, turn upside down.
The jam will keep in the refrigerator unopened for three months.