Legendary Carl Zeiss Jena Pancolar 55mm F1.4 used lens (lens + front cap).

This lens gives you best bokeh in any situation! Typically bokeh lenses are not sharp enoug wide open, this lens is very sharp even at F1.4. It gives organic, cinematic and artistic look all at once. If you had to choose one lens from all the lenses in the world, it would be this Pancolar 55mm F1.4.

Unfortunately, all available lenses out there have turned orange/yellow over the course of 70 years due to the radioactive material used called thorium. In addition to the yellowness making the lens practically unusable in color photography, the yellowness also darkens the lens by one stop.
THIS particular lens has undergone a special treatment (exposed to several different correct wavelengths of UV light for hundreds of hours to achive this), all extra yellowness has been removed.