But, first of all, two or three differently-coloured types of glass must merge. Poc is indeed always characterised by a crystal-coloured layer, to which either one or two layers are added: in the former case, the second colour can be either black or white; in the latter, the lamp is made up of a white, a crystal and a black layer. Design - Design Barbara Maggiolo, 2003. A crystal layer is part of each of the versions, because it corresponds to the internal membrane. The method by which this layer is produced was already known in the field of Murano-glass working, but it had neither been applied to spheres before, or to get such definite lines: this is why it counts among Vistosi's patents. And its versatility earns another point for being available in various sizes and versions: both modern and classic interiors can therefore relish its light, whose intensity changes according to the waves of the membrane.