Start by washing the persimmons thoroughly. Then, core and peel them as you would with potatoes. Chop them into smaller pieces and place them in a saucepan
Add about a cup of water and cook the persimmons over medium heat for roughly 15 - 20 minutes, stirring occasionally until they become soft.
Slowly stir in the 6 and 2/3 cups of sugar until fully dissolved.
Add the lemon juice and increase the heat to bring the mixture to a boil. Let it boil for about 15 - 20 minutes, stirring frequently.
Use an immersion blender to achieve the desired jam texture. Once done, carefully fill sterilized mason jars with the hot jam.