Nice work - very thorough 🙂 I only have a couple of suggestions... 😛

1 - Include headings when you post it - eg:

What Is Sterling Silver?

How Can I Determine an Item I Purchased Is Sterling Silver?

2 - Include a couple of photos if you can (are there any tell-tale signs visually that something isn't sterling? A couple of years ago I bought something advertsised as solid .999 silver, but when I received it there were obvious signs of plating. I wasn't any kind of expert back then, and I'm still not, so that's how obvious it was!).

3. That PS advice shouldn't be included - if it comes down to a PayPal dispute, in 99% of cases the buyer won't receive their money back unless / until they return the item by registered post - something which can be very expensive for overseas post, so instead I would probably just advise factoring that possibility into a purchase decision.