Rinse the blackberries and place them in a small saucepan.
1 cup blackberries
Add the sugar and water to the saucepan and stir until the sugar has dissolved.
1 cup sugar, 1.5 cup water
Turn the heat to medium-high and bring the mixture to a boil.Reduce the heat to low and let the mixture simmer for about 10 minutes, or until the blackberries have broken down and the mixture has thickened slightly.
Remove the saucepan from the heat and let it cool for a few minutes.Use a fine-mesh strainer to strain the mixture into a clean container, discarding the solids.
Let the simple syrup cool to room temperature and then transfer it to an airtight container.