In a small saucepan, bring sugar, water, and rosemary springs to a simmer until sugar is dissolved, then simmer for one to two additional minutes. Remove from heat and let sit for 30 minutes to an hour. The longer it sits the more flavorful it will be!
Strain the liquid into an airtight container to remove any particles and rosemary leaves. Store in an airtight container - like a glass jar - in the fridge. It should last for 3-4 weeks if stored properly.