Quality Check of Jewellery - Step By Step

Hello Everyone.
I am Anand from Bombay (Mumbai). This is suppose to be my first post.

I have been looking for a forum related to jewellery and at last I found one.

I'm going to describe where I am exactly right now in short. I just did a basic training of understanding how manufacturing of jewellery works. After few months I have understood the methods and tools. But when it comes to QC, I'm still not able to understand what exactly is to be checked.
Lets say a goldsmith is working on master for casting. I would check the master if the filing is done properly and by that I check if there are any scratches, uneven surface, proper size of drill for setting and so on.
But then I got stuck when I thought about excess metal? How would I really come to know if there is an excess metal cause I have no idea about the measurements. Like what is the minimum gauge to be used for channel setting or prong setting? if I don't know the actual gauge, I cannot discuss with the goldsmith about the excess metal if there is.
I would want to know A to Z what steps are taken or checked in jewellery when it comes to QC. If there are any ebooks/tutorials (website) or anything. That would also help :)

Thank you and appreciate your time.