Who is the type of person that a powerful Guru looks for in a disciple, as explained by the gem and stone analogy?

According to the teachings in Chapter 19, even a powerful Guru expects specific qualities from a disciple. The ideal disciple is one who possesses wisdom, strong faith at the Guru’s feet, and the courage that is patience. The text uses an analogy to illustrate this: when rubbed on a whetstone, a gem becomes a brilliant jewel, but a stone just becomes smooth. Similarly, a Guru's guidance can only bring out the inherent brilliance of a disciple who, like a gem, possesses these essential virtues to begin with.