To make the pomegranate syrup, combine all ingredients in a small saucepan. Bring to a boil, stirring to dissolve the sugar. Reduce heat and simmer for one hour, stirring occasionally. The mixture should coat the back of a wooden spoon. Remove from heat and allow to cool to room temperature. It will continue to thicken as it cools.
To make the cocktail, combine all ingredients in a rocks glass. Stir gently, until syrup is dissolved. Add ice and garnish with pomegranate seeds.