In a Dutch oven, combine plums and orange juice; bring to a boil. Reduce heat; simmer, covered, 5-7 minutes or until softened, stirring occasionally. Stir in pectin. Bring to a full rolling boil over high heat, stirring constantly. Stir in sugar, orange zest and cinnamon; return to a full rolling boil. Boil and stir 1 minute. , Remove from heat; skim off foam. Ladle hot mixture into 10 hot sterilized half-pint jars, leaving 1/4-in. headspace. Remove air bubbles and adjust headspace, if necessary, by adding hot mixture. Wipe rims. Center lids on jars; screw on bands until fingertip tight., Place jars into canner with simmering water, ensuring that they are completely covered with water. Bring to a boil; process for 5 minutes. Remove jars and cool.