To get juice for jelly, wash plums and cover in water. Boil a few minutes. Cool and strain or put through a sieve.

5 1/2 c. juice
7 1/2 c. sugar
1 box Sure Jell

Bring juice to a boil; add Sure Jell, bring again to a boil; add sugar. Boil for several minutes until juice spins a thread. Let set a few minutes. Skim off top. Pour in clean jars and seal.