Bring to a simmer over medium-low heat, stirring constantly. Cover and simmer over low heat for 1 hour, stirring occasionally.
While figs are cooking, prepare the jars and lids. Put the glass jars and lids (if using preserving jars) in a pot of boiling water, turn off heat.
After cooking the fig mixture for 1 hour, attach a candy thermometer to the side of the pan, making sure the tip of the thermometer doesn't touch the pan's bottom, and continue simmering, stirring frequently, until the mixture thickens.
When the mixture gets quite thick, begin to stir constantly to keep it from scorching.
Cook to 105°C and remove from the heat. Or, test a small amount on a very cold saucer by putting the saucer in the freezer for a few minutes, adding a little of the fig mixture on it, and returning the saucer to the freezer for one minute. When a good gel stage is reached (105°C), the surface of the fruit mixture will wrinkle slightly when pushed with a finger or teaspoon.
Fill the prepared jars with the hot fig jam mixture, leaving 1.5cm headspace. Wipe the jar rims and place the lids on the jars.