Loetz "Fortuna", Blattgrün Verlaufend, PN II-1336, ca. 1904

Thanks to the sleuthing of Deb Fitzsimmons of Loetz.com, we now know that the Spiraloptisch pieces with green spreading to clear have a decor name - that is Fortuna. Fortuna is to Spiraloptisch as Esmeralda or Oceanik are to Wellenoptisch - a version of the basic optic design with added color features. This is a large example - 12" tall - in a shape with plenty of curves and contours to show off the combination of the optic design and spreading "blattgrün" (leaf-green) color, creating vistas of light, color, and shadow.

For more examples of Fortuna, see the decor page on Loetz.com at:
https://www.loetz.com/decors-a-z/fortuna