This is a glass coated with a thick layer of colourless transparent glass, or of a colour other than that of the back.
The first real "sommersi" items were those designed by Carlo Scarpa for Venini & Co . in the second half of the 30's.
They consisted of a layer of coloured glass with the inclusion of air bubbles and gold leaf, more rarely with the subsequent application of rods in pulegoso glass, coated with a colourless transparent layer two centimeters thick.
This technique was extensively taken up by many other Muranese glass factories with very remarkable results. During the 50's Flavio Poli was able to make the best "sommersi" when he was designing part of the production by Seguso Vetri d'Arte , with charming selections of colours, proficiently assisted by the hand of the master glassblower Angelo Seguso .