Some people think you must use pectin to make the jam thick. If you are making a jelly, like my pomegranate jelly, it is mostly juice and sugar. For this to turn into jelly, you do need to add pectin.  If you are an experienced jam maker, then you have probably added lemon zest and lemon juice to the mixture as well. Citrus fruits like oranges, lemons and kumquats are high in pectin – naturally. This is why they are added to jams to naturally add all the pectin you need.