Nice vases, Keith. I have a couple of the yellow vases. Alfredo has some of this type glass under his Czech Jugendstil section. I see them listed as Moser sometimes, but I've never been sure of the attribution. Are yours signed? If you have a good reference, please let me know. I call these pieces lemon glass. I picked up the name from someone, but I don't remember who. The ones I have glow orange under black light, so were probably colored with cadmium. (Thanks, Lustrousstone!)
The red vase is different than the yellow ones. The yellow have internal white spatter used to create the marbling. My red vase is colored on the surface of the white. I see these type vases sold as Loetz carneol on eBay sometimes. They do resemble them. I have seen documentation for these types of vases, but I don't trust my memory -- so much glass, so little brains. The rim is actually pretty nice. It is smooth and feels fire polished. I definitely need to do a better picture. It is black light negative. The weight is pretty normal, neither light nor heavy (221 g, 7.8 oz). The enamel is well fired. There was gilded detail on the enamel, but it has worn with age. It is a nice vase actually. I hope someone recognizes the design.