Hello everyone, my first post here so please be gentle.

I have been wondering about these 925 stamps that I see being sold all over the place, but cant seem to find a answer anywhere.

I am well aware that things that are stamped 925 are not always silver, it makes me cringe seeing the stamps being sold on ebay to scrap dealers, the gold ones too. I am assuming to stamp something thats not silver with 925 would be a trading standards jobby, but what about stamping actual silver 925, is that ok?
I'm meaning over 7 grams in place of a hallmark.

I keep seeing places selling silver jewellery with just 925, which is clearly over the 7grams, I always thought it must be properly hallmarked, but now i'm a bit confused.