Glass carving, vibrating glass.
True cutting is uniform, even though revealing the irregularities of handcrafting, it is continuous and precise, but allows lighter/darker shadings.
The one we are taking into consideration is the honeycomb type: vaguely recalling a beehive which, despite its geometrical suggestiveness, never relinquishes the charm of unrepeatable uniqueness that only the craftsman's hand is able to confer.