Although larger gemstones are generally more valuable, it's hardly worth using them to open the Trial Gate for most people; they're usually just used to feed the Demon Spirits.
When used to feed Demon Spirits, buying smaller rubies is clearly more cost-effective. Therefore, Li Xiu's Ruby Ball, despite appearing priceless, is quite the challenge to sell.
If sold cheaply, Li Xiu wouldn't be willing; if sold expensively, no one would want to buy it unless they encountered a wealthy buyer. Otherwise, it's quite difficult to sell this thing.
"Where can I find a big-time wealthy buyer willing to pay the price?" Li Xiu thought over and over. Most of the people around him were similar to him, nearly all poor, except for Chu Jun, who was super rich.
So, Li Xiu planned to hand over the task of selling the Ruby Ball to Chu Jun, hoping he could find an appropriate buyer.
After assigning the task to Chu Jun, Li Xiu then asked Sha Chu to help him purchase black spinels.