Why does the hardware jewelry factory charge for proofing

Question: I am looking for a custom ring, the quantity is 500, but why do I charge for it? Answer: Any hardware jewelry factory will charge a certain amount of processing fee for developing samples. This is an unwritten rule of the hardware jewelry factory, and it is also a production process. If no processing fee is charged, some customers only make samples, but do not produce bulk goods, or At the same time, I found several factories for proofing, which eventually caused many factories to make free samples. The symbolic fee (usually 300-500 yuan, but the actual cost of proofing is far more than this) is a constraint on customers. The processing fee will be refunded when the bulk product is made. The information comes from the Internet, please contact if it involves infringement. Previous: What to do if the ring size is too big