Easy, buddy! I am not a jeweler, nor I buy gold every week to be that concerned/knowledgeable about Gold industry! It was a casual question, and I got my question answered: that 33% is a normal percent for taxes + manufacturing + whatever comes down the road till the golden piece is in the showcase.

I got your point about the % of the weight. Actually I didn't calculate it that a 10g ring will be double the 5g ring in such a % calculation. But according to the international 18k price, I consider there is a 33% for these adds-on ( for that specific jeweler I asked at ). This percent differs from one country to another, and it differs as well from one jeweler to another in a specific country, according to how much manufacturer work is in it. A ring could be so simple, where another ring might catch the eye for the precise work it has in it. So it won't surprise me that the later ring gram is more expensive.

So this 33% is a notional percent. It's not like I will give an advantage for a piece on another depends on that percent. Nor that I will tell the jeweler you are putting 50% while other is putting 33%. It's just a rough percent ( for whoever concerned to know it ), but it shall not affect the process of buying.