Germany, about 1770. The peculiarity of these two copper glasses is the construction of the lens called ”facetten glaser”, due to the type of manufacture. The glasses with yellow silk on the nose are very rare, as it is made with plano lenses. The lenses are slightly darker but not too much to protect from the sun and that’s why the glasses was described as ”conservative”. Used to preserve the eyes during the reading from the white paper. Held in their double ray-skin case.