[Eileen]

I normally only use the flat marvers, not specialty ones, but one thing we all had to learn was patience while the glass melts. And the larger the bead, the longer it takes. You may want to use something to preheat the glass so that it is already part way heated. Stick the ends into the bead door of a kiln, or use a rod warmer (beauty supply tool warmers are the same, but they get HOT on the outside too so be careful not to touch or put it close to anything flammable ~ says someone who reached over & crisped the skin on the bottom of my arm when I touched it to the top of mine)
Some colors do melt easier than others (like ivory for instance), but I don't know about Devardi colors.