The aroma of citron zest is a dazzling, vivacious burst, piercingly bright and intensely tart, immediately invigorating the senses. It possesses a crisp, almost metallic edge that differentiates it from the softer, sweeter aspects of lemon or lime. There's an underlying green, slightly bitter nuance, reminiscent of the waxy outer peel and even a hint of the pith, which adds complexity and an authentic, naturalistic feel. Its initial projection is expansive and effervescent, like a shower of freshly grated peel, sparkling in the air. As a quintessential top note, its most vibrant facets are fleeting, yet its greener, more aromatic heart can subtly weave into the initial stages of the dry-down, lending a sustained, clean freshness to the composition. It's sharp without being harsh, clean without being sterile, and remarkably uplifting.