Nguyet or Kim or Vong Nguyet Cam or Quan Tu Cam is a musical instrument of chordophonic family of the Viet ethnic group. he surface of Nguyet, round-shape, is made of light, soft and non-decorated wood and 30 cm in diameter. On its surface a part, called the head of the instrument (Thu), is used to hook the chord.

The side of the instrument is made of hard wood, 6 cm in height. The bottom is covered with wood without sound hole. The neck, 100 cm in length, fixed to 10 frets at pentatonic scale (7 are fixed to the neck and 3 are fixed on the surface). The head of Nguyet is put four tuning pegs but only hooked two silk strings (nowadays, nylon string is used). The two strings are tuned at a perfect fifth Fa-Do1; Sol-Re1 or a perfect fourth G-C1; D1-G1. In the past, instrumentalist used his/her fingernails to play Nguyet. Nowadays, they play it with a plastic or tortoise-shell plectrum. Nguyet has range of more than two octaves.

Nguyet is used to accompany Van singing, Hue singing, Tai tu singing, Bat am music, ceremonial music and traditional stage orchestra.

Today, masterpieces for Nguyet have been composed by many musicians to perform as solo such as Que Ta (My homeland), Chung mot niem tin (the same faith) by Xuan Khai; Tinh Me (the affection of the mother) by Tran Luan; Tinh Quan Dan (soliders and people relationship) by Xuan Ba...