This set has taken quite a while for me to assemble. The chalky blue one on the left I have owned for a number of years, possibly coming from the collection of Jim Blackie. The one on the right was purchased at the recent Dixie Jewels Insulator Collectors swap in Mountain Home, NC. Funny how it works, I actually purchased two of the cobalt ones at that swap, from different dealers. The cobalt one is incuse marked on the skirt, but the marking is very shallow. It does show up slightly right at the vertical line where the sunlight is hitting the skirt.