Start by making your rosemary syrup. 

1. In a pot, combine 1 cup of water, 1 cup of sugar, and rosemary sprigs.
2. Boil until the sugar dissolves. 
3. Bring to a simmer, for about 1 minute. 
4. Turn off the heat and let steep for 30 minutes. 

The next step is to make the cucumber rosemary juice. 

1. In a blender, combine 1/2 large cucumber, 3-4 sprigs of rosemary, and 1/2 cup of water.
2. Blend until smooth and strain. 

The last step is to combine all of your ingredients in a cocktail shaker. 

1. Add your gin, lemon juice, rosemary syrup, and cucumber juice.
2. Add ice. 
3. Shake well and then strain into a glass with ice. 
4. Optional: top with sparkling water. 
5. Garnish and Enjoy!