Standard clear glass isn't actually totally clear.
You might notice a slight green tint to the glass or
green edges. The green tint becomes even more
prominent when looking at an angle and gets darker
as glass thickness increases. The green tint is due
to the natural presence of iron oxide from elements
such as sand, or from the cask or container in which
the glass was melted.
iron (or starphire) glass, on the other hand, is completely clear.
This is achieved by reducing the amount of iron in
the molten glass formula, providing optimal,
unobstructed views. In addition to unobstructed
views, the edge work on low iron glass is much less
green than standard clear glass. Low iron glass has
a visible light transmittance (VLT) of 91 percent in
a standard quarter inch thick glass, while standard
clear glass has an 83 percent VLT, making it the