You need to buy about 3 pounds of plums, cut them into 8ths and toss out the pits. Make sure they are ripe. Put the plums in a big stockpot with 1/2 water and a teaspoon of lemon juice. Bring to a boil using medium high heat, stir. Once boiling, reduce the temp to medium and continue to stir, cook for 10 minutes. You’ll end up with the syrup. You can strain it if you like, but, I prefer not to. Add 7 1/2 cups of sugar, stir until resolved. Remove the foam from the top of the mixture. Add the mixture to sterilized glass jars. Be sure to wipe the rims of any of the plums jelly that may have spilled to ensure a good air tight closure. When you have them all filled, screw on the lids and the rims and put in boiling water for 5 to 10 minutes. Remove from water and allow to sit for several hours. Check the seals and make sure the lid does not pop up when pressed on. You can store them on the shelf for up to one year.