I found this piece in an antique shop as the body of a lamp. I got it for only $48 dollars, a steal considering this tube went for $595 when new in 1953! The amber coloration is caused by the heavy X-Rays and the iridescent sheen by tungsten deposits from the hot electrodes after many, many years of heavy use. This tube probably helped save thousands of lives. Rated 80-120kV, 15 mA