Closest in result to Warm Yellow, this exquisite Revolution 33 graduate is the opalescent yellow I have waited for.  Where continuously working Warm Yellow will yield you light blues and purples, Singular Passion will go from transparent to opalescent or milky in color, but stays in the golden and white-ish yellow range of color.  The result is gorgeous.  I tend to like the results of Singular Passion best after a sculpture, either hollow or solid, has been worked in the flame for an hour or longer.  Kiln striking at 1050 F or higher will shift the color when its is allowed to soak for a duration of time.