Selects ripe, even overripe plums (if they have damaged parts, they are removed). Washed and boiled in very little water, maybe just without water in their own juice. Rub through a sieve or colander to remove skins and stones. The resulting slurry is concentrated in large shallow pans with constant stirring with a wooden paddle. Stirring, until done with the blade groove joins slowly. Then marmalade enough compressed and received brilliance. The finished jam is still hot pour into dry containers. Leave open a few days to catch the crust, then closes. Store in dry and cool place. At the end of cooking and Jam can be added sugar - usually up to 25% by weight of the finished product.