Just my opinion, but out of courtesy I think one of the contributors to this thread - at least those who consider they know what they're talking about - which excludes me - should respond to the helpful comments from Jonas. Whether Jonas is correct or not, politeness should dictate that his help is acknowledged.
My knowledge is very limited here, so some illumination wouldn't go amiss re the colour construction of these things. Is it legit to describe all similar pieces from whatever origin - whether one submerged colour, or two - as sommerso. In other words if we have simply clear casing over blue, does that qualify, or is it the case that two submerged colours are required in order to fit the bill?