Add Cherry Balsamic, lime juice and sugar to a sauce pan and simmer until sugar is completely dissolved to make a simple syrup. Remove from heat and allow to cool completely.
When ready to serve, add the Cherry syrup, gin, and lime juice to your favourite pitcher.
Fill each glass with ice and then pour ¼ cup of the gin mixture into each glass. Fill the glasses with tonic water, stir and serve with lime wedges.
Finish with a drizzle of grenadine if desired.