Any bramble fruit, fresh or frozen, wild or store-bought, will work with this recipe. Blackberries, blackcap raspberries, regular raspberries, dewberries, cloudberries, salmon berries, thimbleberries, etc. My method works really well for any normal kitchen. But, for those of you with fancy juicers, you can pretty much make an instant puree/juice from your blackberries. Just measure out equal parts blackberry juice to sugar, heat the mixture to dissolve the sugar, then strain and put in jars.
Some people want a less-sweet syrup, which is perfectly fine. You can add sugar to taste if you want. The tradeoff is longevity. If you don't use this much sugar, your syrup will not store as long; sugar is a preservative. Done my way, this syrup will store in the fridge a long time, easily a year or more.