Our current practice is to buy the precious metal once we get the customer's order as the price fluctuates every day.
Thereafter, advise the customer of the final price once the metal is booked.
That will be the most accurate cost.
We can reverse the flow but we need to confirm the order fast in order to secure the price quoted.
However, this might not work with 878(4X) as the process flow in China is totally different.