Ruby was a catalog color from 1938 to 1942, 1945 to 1950, 1984 and 2000 to 2011. This highly desirable color can be produced in several ways, but the best reds seem to come from the addition of gold to the metal (melted glass.) I don’t know if Blenko ever used gold but I am guessing that Selenium was their colorant of choice to produce the recent pieces of Ruby glass. In November of 2011, Blenko management told me that they were discontinuing Ruby because “it was too difficult to get the color right.” If you do not own one, get one now.
Glass color is not as simple as just throwing in some chemicals and the color magically appears. Things that can affect the color of glass are:
-Type, amount and concentration of the colorant.
-Temperature of the melted glass.
-Temperature reached when glass is reheated to work it or finish it.
-Temperature of the lehr (annealing oven.)
-Duration of the melt.
-Number of times glass is melted. Generally, more melts mean darker hues.
These things all make glass color variable and sometimes impossible to identify with certainty.
Blenko did not make Ruby glass in the colder months so I assume that it is very temperature sensitive.
Who knew that Ruby glass would fluoresce under a black light?