What glass is used for serving a Separator cocktail?

The Separator cocktail is traditionally served in a cocktail glass, which is specifically designed for cocktails that are meant to be served chilled and without any ice. This type of glass, also known as a martini glass, has a wide bowl and a narrow stem. The shape allows for the drink to be enjoyed without the distraction of ice, enhancing the experience of the cocktail's flavors and aromas.

The other glass types mentioned do not align with the typical serving style of the Separator cocktail. Hi-ball glasses are taller and often used for mixed drinks that include a significant amount of mixer, Collins glasses are similarly tall but more narrow, usually for drinks served with ice, and rocks glasses are short and wide, primarily used for spirits served over ice or cocktails that should be served on the rocks. Each of these glasses serves different purposes based on the type of drink and its intended presentation, making the cocktail glass the appropriate choice for the Separator.