The Bijou, a cocktail named after the french word for jewel, or rather 3 jewels, is the perfect blend for this aperitif:
Green Chartreuse as Emerald
Sweet Vermouth as Ruby
Gin as Diamond

BijouAll mixed in equal parts with a dash of orange bitters, this drink is a perfect mix of mellow and vibrant.  It blends the characteristics I love about so many drinks:  the sweet butteryness that vermouth brings to the Negroni, the herbal brightness of the Green Ghost, and the orange bite in the Aperol Spritz.  They all blend together in this light & delicate cocktail which is kind of amazing how each ingredient plays off of the other.  At first thought you’d think the Green Chartreuse would overtake the cocktail but the vermouth really works to balance it out.  The gin and orange bitters follow it, adding a citrusy twist, which leaves you with the same clean finish, like you were drinking a sorbet.