Briefly rinse the currants, then drain well. Remove the berries from the panicles with a fork. Fill the berries into a clean, well-sealed jar, add the rock candy and the raspberry brandy. Close the jar and place in the sun for 2-3 days so that the color and aroma are well extracted from the currants. Shake a few times in between.
Leave the jar to cool for 4-6 weeks. After this time, filter the liquid from the jar through a fine gauze cloth, fill into clean bottles. Carefully close and mature in a cool, dark place for a few more months.