The glass artist has to make two separately blown cups of glass which must be the same width at the base or top where it is to be fused to another piece of glass. The second piece must be placed directly at the edge of the first piece with no overlap of the edges. Compare this to our Burmese glass where the pink top is made of pink glass over the cream glass, put back to the flame and fused.
The finished piece can have two or three coloured sections of glass and it must appear as though it is one piece of glass. From Venice, the method of making incalmo spread across Europe to America where this glass ware is still made by skilled artists.
So just to end on a uplifting note, when I was reading various sites about this glass I came across another innovation and, dare I say, it had to be America. I was struck by the name "memory glass" and it comes in hearts, orbs or pendants and, wait for it, within the blown glass is suspended the ashes of one's beloved departed. As the site put it, "...a beautiful keepsake memoir piece which can be displayed in one way or another." I think I'll give this one a miss. I do enough talking to the departed without having them swirling around in a paperweight which I'd have to dust.