Prepare the syrup. Mix sugar and water in a saucepan. Bring to a boil over medium heat, cook for 1 minute. Cool the syrup to room temperature. This will take about 40-50 minutes, depending on the room temperature.
Make a berry liqueur. Place the crushed grapes in a 3-liter jar, pour in the cooled syrup. Close the lid tightly. Let it stand in a dark place for 1-2 days so that the berries give juice.
Prepare the liqueur. Pour vodka into the jar with the berries, close the lid and leave to infuse at room temperature for 2-3 weeks. Shake the jar every 2-3 days.
Finish making the grape liqueur. Strain the resulting drink through a fine sieve, then through a gauze filter. Pour the liqueur into clean bottles, close the lid tightly and let the infusion sit for another 7-10 days.