My family loves this syrup. I make it for breakfast whenever blackberries go on sale at our local grocery store. You can also serve this as a desert over sponge cake or angel food cake with whip cream or vanilla ice cream.
Rinse blackberries. Squeeze 1 cup juice from blackberries. This can be done by mashing them through a strainer with a potato masher. It's kind of difficult and messy. I just run mine through the juicer. You want the juice, not the pulp. I get little more than a cup out of a pint and a half of blackberries.
Pour blackberry juice, lemon juice, and sugar into a sauce pan. Bring just to a boil. Reduce heat and simmer for 3 minutes.
Add a tsp of fruit pectin to thicken a bit more. Pour into an air tight container (I use a mason jar) and store in the refrigerator for up to 1 week.