A 'grail bag' is any bag a collector desires above all others — named after the Holy Grail of Arthurian legend. The term captures the combination of aspiration, difficulty of acquisition, and emotional significance that characterises these pieces. For one collector, a grail might be a specific Hermès Birkin in a discontinued colour; for another, it might be a Chanel Classic Flap from the 1990s.
Grail bags are different from investment bags: they're defined by personal desire rather than financial logic. Owning your grail bag is often a significant milestone in a collector's journey, and the pieces themselves tend to be kept in the best condition, used most carefully, and never sold.