Below is a collection of microscopic photos of a set of yuesheng strings. This set is a metal-nylon guqin string set, and is a typical construction for metal core qin strings. I bought this set for about $30, and it seems like this is a lower end but affordable qin string set. Compared to the dunhuang strings I have tried, I found these a significant improvement. They were much less stiff and were longer, which made stringing much easier. These strings have the characteristic metallic overtone commonly present in metal-nylon strings.
I bought these strings originally to complete the buzz checking phase of my qin, and to use them initially to start learning, as at the time I did not have access to composite strings such as Longren Binxian, and silk was too expensive. Fortunately, my experiences with these metal-nylon strings, and the lack of availability for other strings pushed me down the path to start researching and making my own alternative qin strings. From this endeavor sprouted the need to analyze the harmonic content of strings to better understand what made them work and sound the way they did, and to further improve development in qin strings. I have the complete harmonic analysis dataset for these strings on my qin, though like other metal-nylon strings, I no longer use them due to potential damage to the finish of my qin, as well as having access to much better quality silk strings.
Like the photos for my Dunhuang set, I have taken some additional photos of one of the now-destroyed strings for this set, string 7. You can see again the very typical four layer construction of this string, which consists of a nylon ribbon outer wrapping, a second nylon ribbon wrapping underneath wrapped in the opposite direction, a third layer of nylon fibers, which are twisted around the last part of the string, the monofilament steel core. You can click on the photos to enlarge the pictures.