The previous identification for 004 (from fossilfly) indicated 'LAG srl'
Zonca is not known as a glass furnace on Murano. It seems to be a lighting company, based in Alessandria, IT which made various mushroom lamps etc on Murano, but also (later) made lamps and lighting in various materials.
Melogranoblu, was/is another lighting designer (from Bergamo) whose products sometimes carry this number on the glass parts.
Born in 1967, the LAG company is listed as making float glass at their Venetian (not Murano) factory, but it seems that they were also producing and selling (blown) lampshades and bases sold to /made for lighting design companies.
In order to qualify for the Municipal VM (numbering/labeling) scheme, they must have owned a site on the island of Murano making (blown) glass, but whether it had the name 'LAG' over the door? whether it had another name? was it taken over from, or by, somebody whose name is well-known? What was the exact address of the LAG-owned furnace on Murano? Is it linked to 'Laguna'?