This decanter set from the Diamond Glass-Ware Co. appears in a 1919 Butler Brothers catalog, so it is quite probably on the "late" side of Carnival glass made in the USA. The collectors call it Golden Harvest because it's most often seen in Marigold Carnival, but it does come in Amethyst Carnival, too.
The Fenton decanter is made with a mould we bought from the L. G. Wright Glass Co. in 1999. I will check the mould and report further, as it could be the original Diamond mould since Wright acquired quite a few original Dugan and Diamond moulds in the late 1930s.