Wash and pit the cherries.

Chop the peppermint coarsely and place in a burlap spice bag.

Warm the simple syrup and add the peppermint bag, cherries, and preserving sugar.

Cover and chill overnight.

On the next day, remove the peppermint bag (squeeze it out well), bring the cherries to a boil and let boil for 5 minutes.

Blend and sieve.

Fill hot rinsed canning jars with the hot marmalade, close tightly, and put in a cool place