"This stuff [metallic glass] is generally shiny black in color, not transparent, due to having a lot of free electrons (think of mercury in an old thermometer)."
However, this contradicts the second paragraph of TFA:
"The finding could lead to aircraft that look like Wonder Woman's plane. Such planes could have wings of glass or something called metallic glass, rather than being totally invisible."
So... shiny black stuff is not totally invisible... got it.
Slashdot Mirror
Looks like it isn't transparent, from TFA:
"This stuff [metallic glass] is generally shiny black in color, not transparent, due to having a lot of free electrons (think of mercury in an old thermometer)."
However, this contradicts the second paragraph of TFA:
"The finding could lead to aircraft that look like Wonder Woman's plane. Such planes could have wings of glass or something called metallic glass, rather than being totally invisible."
So... shiny black stuff is not totally invisible... got it.