In a classic Aviation cocktail, which purple liqueur gives the drink its violet color?

In a classic Aviation cocktail, crème de violette gives the drink its violet color.

The Aviation is a gin-based cocktail mixed with lemon juice, maraschino liqueur and crème de violette. The floral liqueur is responsible for the drink’s distinctive pale purple or lavender appearance, as well as some of its violet aroma.

The cocktail was created in the early twentieth century and is commonly associated with Hugo Ensslin’s 1916 book, Recipes for Mixed Drinks. Some later versions omit crème de violette because the liqueur became difficult to obtain for much of the twentieth century. Those versions are usually paler and taste less floral, but they are still sold as Aviation cocktails.

Crème de violette is not the same as crème de cassis, which is a blackcurrant liqueur, or blue curaçao, an orange liqueur colored blue. Maraschino liqueur is another essential ingredient in many Aviation recipes, but it is clear and does not supply the cocktail’s violet color.