Soooooo .... (admitting my ignorance) .... can someone explain 'sommerso' please? I thought it was 'layered' glass. Am I right, or does there have to be a minimum number of layers to be classed as 'sommerso'? Like, is one layer of colour and one of clear still sommerso, or does there have to be more? And is the term sommerso just used to describe italian (Murano?) glass, or is it still called sommerso even if it's Scandi or LSA or whatever?