Combine raspberries, honey, lemon juice and water in a saucepan over medium-high heat and bring to a boil. Reduce heat and simmer gently until the berries are completely cooked, about 5 minutes. Remove from heat and cool. Strain the mixture through a fine sieve into a pitcher, using a rubber spatula to press as much liquid as possible from the fruit. Discard the pulp. To serve, fill a tall glass with ice and add three tablespoons of the raspberry syrup. Top up with ginger ale and stir. If desired, garnish with fresh raspberries and a lemon wedge.