Da Mao was an expert in the trade of stone gambling. After his interaction with Li Du, he started to hold the latter in high regard. Da Mao came to the conclusion that although Li Du lay low, he was actually very capable, a lot more than himself.
Li Du's capabilities showed in a few areas. For example, when they had to mill the stones, there were a few times where he could not locate where the jade was. Li Du, on the other hand, could draw a precise line leading to the jade.
In another instance, Da Mao had been indecisive over a few stones. After Li Du saw those stones, he made up his mind to buy them. In the end, the stones were indeed valuable.
Hence, after Li Du questioned him, Da Mao started to feel doubtful. He stuttered, "As for that, that should be it. I think it is. In any case, I think seventy or eighty percent of it would be water foam, not worth the risk."
Li Du asked, "How can you tell?"