That's Pretty Shifty!
Shifty and CFL are two terms to describe the same thing — a pallet of glass that changes color based on the light that it is under. CFL stands for “compact fluorescent light.” The glass changes its apparent color in fluorescent lighting. The first CFL/shifty glass was done by Glass Alchemy in 2014, with the color Serum. Next, came Terps. These are a bit tough to get, but other CFLs are available: