"Part of the modern mixologist’s art is to play with these variations of time, combining the liquid of ferment with the vital juice just squeezed from the freshest fruit. Accordingly, you need to get things just right to make a proper Black Diamond. John deBary of the Manhattan bar PDT doesn’t serve the drink he invented all the time—only when blackberries are at their peak. Thus, to experience this exquisite potion as its creator intended, you have just a three-to-four-week window in the summer. Timing is everything."