The purple haze cocktail isn't considered a layered drink, and even though it's not a drink that uses liqueurs with varying alcohol content to create a layered effect, it relies on the same principle. Black raspberry liqueur, the "purple" in purple haze, has a higher specific gravity than vodka, lime juice and simple syrup, the drink's other components, so it sinks to the bottom of the glass where it partially disperses, creating the "haze" in purple haze. Fluid dynamics aside, a purple haze takes less time to make than it does to explain why it's called "purple haze."
Add ice cubes to a cocktail shaker along with 6 parts vodka, 2 parts freshly squeezed lime juice and 1 part simple syrup.
If you're making a purple haze by the shot, add 1 1/2 ounces of vodka, 1/2 ounce of freshly squeezed lime juice and 1/4 ounce of simple syrup.
Shake the cocktail shaker to mix. Pour the mix in a chilled shot glass.
Pour one part, or about 1/2 tablespoon, of black raspberry liqueur down the inside of the shot glass, not directly into the drink. Pouring down the side of the glass gives the base of the shot a hazy purple color.