This 3 Ingredient Tropical Blue Margarita is made with blue curacao liqueur, which gives it that gorgeous tropical blue color, this margarita is a show-stopper! Made either on-the-rocks or frozen, this blue curacao margarita will make the perfect summertime drink! Agave nectar is a sweetener often used in margaritas and other cocktails. I personally don’t add it to my margaritas (I don’t enjoy the extra sweetness), but if you like a sweeter margarita, this is the preferred sweetener.