|Like marigold, the clambroth color is the result of the iridescent spray being applied to clear glass. Collectors consider most clambroth to be a distinct color, similar to marigold but lighter. It's usually more yellow and quite transparent. Above left are Imperial Lustre Rose tumblers in a pretty good marigold and a good clambroth. Above is a Northwood Peacock and Urn bowl in clambroth. Notice that it has a more satin finish than most Imperial.
At the left is an Imperial Windmill bowl in clambroth that shows the predominant yellow pretty well. Imperial made the bulk of the items considered clambroth. Most companies made some clambroth, though a few collectors dispute whether all of it was an intentional treatment or simply a weak application of the marigold spray.