The ruan is a Chinese

Traditional Chinese musical instruments

-The Eight Sounds or Eight Tones :The eight categories are: silk, bamboo, wood, stone, metal, clay, gourd and hide. There are other instruments which may not fit these classifications. This is one of the first musical classifications ever.-Silk :...

 plucked string instrument

String instrument

A string instrument is a musical instrument that produces sound by means of vibrating strings. In the Hornbostel-Sachs scheme of musical instrument classification, used in organology, they are called chordophones...

. It is a lute

Lute

Lute can refer generally to any plucked string instrument with a neck and a deep round back, or more specifically to an instrument from the family of European lutes....

 with a fret

Fret

A fret is a raised portion on the neck of a stringed instrument, that extends generally across the full width of the neck. On most modern western instruments, frets are metal strips inserted into the fingerboard...

ted neck, a circular body, and four strings. Its strings were formerly made of silk

Silk

Silk is a natural protein fiber, some forms of which can be woven into textiles. The best-known type of silk is obtained from the cocoons of the larvae of the mulberry silkworm Bombyx mori reared in captivity...

 but since the 20th century they have been made of steel (flatwound for the lower strings). The modern ruan has 24 frets with 12 semitones on each string, which has greatly expanded its range from a previous 13 frets. The frets are commonly made of ivory.