A diamond ring fell in the hotel room. How long does it take for the police to file a case and give an answer?

Mainly depends on the workload. The answer can be given within 1-3 days.

The police will immediately check the public video of the hotel and ask the hotel to check it carefully. The hotel will quickly find a cleaning attendant to verify the situation.

After staying in the hotel, keep your valuables close to your body, and remember to check whether the items are complete when you leave. Valuables are best stored at the front desk of the hotel. In fact, almost every hotel has such a reminder. On the one hand, the two parties form a custody relationship invisibly, and the hotel has the obligation to undertake custody; On the other hand, because both parties have checked and verified, they can determine the specific items that were lost or stolen at that time. In fact, the safe in the room belongs to self-care, and the hotel will not be liable for compensation unless there is evidence to prove that the hotel has violated its security obligations. Moreover, even if the responsibility is investigated, it is easy to cause controversy because the specific matters cannot be determined.