Stunnner was settled in the mid-1880s with a post office first being established in 1886. Similar to other towns in the area like Platoro, there isn't much information about the early years of Stunner.
Stunner had similar periods of activity as Platoro, framed by the post office's years of operation from 1886-1894 and 1913-1914. The only photos I could find of Stunner were from the period around 1913.
The 1917 publication Geology and Ore Deposits of the Platoro-Summitville Mining District, Colorado by the Colorado Geological Survey gives the following information on Stunner.
Following the discovery of rich ore deposits at Summitville, vigorous prospecting in the regions adjacent to this district resulted within the next ten or fifteen years in opening up other properties in various places in the Alamosa valley and local centers of industry were established at Jasper and Stunner.
Today Stunner is a ghost town with no remaining structures. A Forest Service campground is located adjacent to the town site.