Place the pomegranate juice and sugar in a saucepan and heat over medium heat. Whisk until the sugar dissolves, then bring to a simmer and let it bubble for 4 to 5 minutes. Remove from the heat, stir in the lemon juice and let sit until it cools to room temperature and is syrupy. This stores great in a the fridge for a few weeks.
Fill a glass with crushed ice. Shake the orange juice and tequila together in a cocktail shaker with ice for 30 seconds. Pour over the crushed ice. Drizzle in the grenadine. Top with a few cherries and a sprig of rosemary to be festive!