The red string is not specifically a Chinese object. Versions of it appear in Chinese, Japanese, Korean and Indian custom — in the Chinese telling it is tied at New Year and worn until it falls off on its own, and a red cord is specifically associated with a benmingnian year. We sell it as a piece of custom with a documented use, not as a device.
We use silk, which knots and drapes better than nylon and ages visibly: a silk cord will fade and fray within roughly a year of constant wear. That is expected. Nylon holds its colour longer but slips, and the sliding knot on a nylon cord works loose.
The jade bead is nephrite, grey-green, and each one varies slightly in tone.