ice cubes, or as needed
1 1/2 (1.5 fluid ounce) jiggers gold tequila
2 (1.5 fluid ounce) jiggers sweet and sour mix
1/2 lime, juiced
1 packet artificial sweetener (such as Splenda®)
6 fresh blackberries
Fill a cocktail shaker with ice. Add tequila, sweet and sour mix, lime juice, sweetener, and blackberries. Put lid on shaker and shake.
Fill margarita glasses with ice. Pour cocktail into glasses.