There were three blues used for Azurene: Azure, Blue and Royal Blue, with Azure the lightest and Royal Blue much the darkest shade. I have Blue and Royal Blue in my collection, but as has been noted I haven't yet photographed them. Royal Blue is not, in fact, listed by the studio as an official colour, but I have seen a couple of pieces in this darker shade. It is not Black Azurene in a different light. Royal Blue is rather like Bristol Blue glass in colour. I'll try to remedy my omission on my web site asap.
Anton