This art-glass disc is made with two very important techniques: the first one is the "sommerso" technique; the fishes and the seaweeds in the middle of the dics are overlaid or "submersed" by a layer of clear crystal, so that the colours inside are magnified. The second technique is called incalmo and allows a single piece of glass to be made up of two distinct colours and two distinct techniques. The actual composition of the brighting colours is a jealously-guarded secret, carefully handed down from generation to generation. The diameter of the disc is cm 41 (15.75").