Use a microplane to finely shave the tonka beans. Combine the sugar and water in a small saucepan. Place over medium high heat and add the shaved tonka beans. Bring to a boil, stirring occasionally until the sugar is completely dissolved.
Remove from the heat and cover. Let steep for 1 hour and then strain the syrup through a coffee filter. Cool completely before using. This syrup will last for 2 to 3 weeks in the fridge.
Felix Felicis Cocktail
In a cocktail shaker combine the barrel aged gin, apricot brandy, tonka bean syrup, lemon juice, bitters, and luster dust. Add ice, cover, and shake for 10 to 15 seconds. Strain into a coupe glass. Stir the cocktail just before serving to create a shimmery effect. Enjoy!