Prepare water bath canner (according to the instructions above) and get the jars & lids ready. Combine the plums & sugar in a large pot. Cook on medium heat allowing plum juices to release. Slowly bring to a boil and add lemon juice, cinnamon, nutmeg and cloves. Let the sauce cook over med-high heat for 15-20 mins stirring frequently until it looks syrupy. Add the pectin and bring to a strong boil for 5 mins until it's thick and shiny. (be sure to read your pectin instructions as they differ in method). Remove the pot from the heat & ladle the jam into the prepared jars. Wipe the rims, apply the lids & rings and process in a boiling water bath canner for 10 mins (adjust the time with altitude).