In the summer of 1950, Armstrong decided to attempt to use the glass left in the furnace during a change from clear to amber. This resulted in these darker colored DP1s. It seems that the green smoke examples constituted the bulk of the production during this period, but there are a variety of tones that can be found. I don't see smoky amber listed in the price guide, but rest assured that this is a completely legitimate unaltered insulator bearing mold number 13 with a 1950 date code. If you want to start a string of colored DP1s, here's your chance. $13 for this mint pair, plus postage.