This color is similar to some shades of Limelight or Zircon, but it has more of a blue tint. It, too, is in limited supply. Albemarle 5 oz. This glass will glow bright yellow under a black light. The pieces will usually be accessories, such as vases and compotes.
Cobalt is, as the name implies, a very deep shade of blue.
Please note that the above is not a complete listing of Cobalt items. This was a late color, still produced at the time of Heisey's demise. It is like smoke or a dark gray, and is sometimes referred to as charcoal. Limited in production, Dawn shows a shade of amethyst when held to natural light. The color is similar to Imperial's gray.