<human>: Hi Reddit!

I have fortunately found the girl I love and we are engaged -- one of the things we're doing at the moment among the myriad of wedding-related brou haha is starting to think about our wedding rings.

I personally think jewelry should have some character to it, and I plan on wearing this thing for a while, so I have a design that is of no consequence to my question.

What I want to understand is, how much should I expect to pay for a ring if it was made in platinum. I have found this information to be sort of difficult to come by, and there is a lot of differing statement about platinum's cost relative to gold. I'm not really interested in the qualities of the metal, as I understand that mostly. Here's the skivvy:

My ring would hopefully be approx **8mm** in width, for a ring size of **8.5**
Her ring would be about **2mm** in width, and her ring size is about a **4**.

I don't know how many ounces of metal it would take to create a ring like that, and so it's hard to determine from the price-per-ounce of platinum what I should expect. As I live in a metropolitan area, it's really easy to get ripped off for things like this. So I am hoping that some kind redditor jeweler who has no stake in my sale might be able to give me a quick guess as to what range each of these would be in!

Thanks for reading!

Can you succinctly summarize the text in 1-3 sentences?
<bot>: I'm getting married, yay! I don't want to get ripped off. I'm hoping someone knows how to determine how much metal goes into rings!