To make the blueberry vodka: Pour out approximately 1/3 of the bottle of vodka into a holding container; set aside. Score each blueberry with a small nick and place into vodka bottle. With the vodka previously set aside, fill the vodka bottle until just below the neck. Add just enough raspberry liqueur to top off the bottle. Let sit in a dark place for 2 weeks.
To make martinis: In a cocktail shaker filled with ice, combine 2 parts blueberry vodka, 1 part raspberry liqueur, and a dash of lime juice. Shake vigorously and strain into glass. Garnish with twist of lime zest.