In traditional Japanese aesthetics, wabi-sabi (侘び寂び) is a world view centered on the acceptance of transience and imperfection. These pieces have small imperfections that contribute to the overall beauty of the piece.
Here are some examples.

Wabi Sabi Periwinkle Handmade Glass Plate 10" x 10" (25.4 cm)
(The waves on the left side are due to firing but contribute to the overall composition)

Wabi Sabi White Handmade Glass Plate 6"x 12" (15 x 30 cm) SOLD
(There's small buckle in the white field)