Combine peppers, vinegar, and sugar in a large Dutch oven. Bring to a boil over medium-high heat; boil 9 minutes. Reduce heat to low; simmer, uncovered, 5 minutes. Add liquid pectin to pepper mixture; return to a boil and boil 1 minute. Reduce heat to low, and simmer 4 minutes. Remove from heat, and skim off foam with a metal spoon. A drop of green food coloring can be added if you want it greener.