Mouth-blown glass carries small variations in wall thickness that machine glass cannot, and those variations are what the light shows. Lit, the glass glows unevenly at the edges and thickens the light at the base, which is why a blown shade reads as warm even at a cool colour temperature.
Most of the pieces here are made in the Veneto, many in Italamp's own workshops, where the glass is blown hot and then worked by hand before assembly. Small variations in colour, bubbles and line are part of the process and are not faults.