Place 3 cups cucumbers in a medium glass bowl, tip with 1 cup onion. Repeat procedure with the remaining 3 cups of cucumbers and 1 cup of onion.
Combine vinegar and remaining ingredients in a small saucepan; stir well. Bring to a boil; cook 1 minute. Pour over cucumber mixture; let cool. Cover and chill at least 4 days.
Note: Pickles can be store in the refrigerator for up to one month.