Hello, first post on the forum (!) so hello everyone. Apologies in advance if I've got something wrong forum-wise.

So it's a bit of a long shot but I'm hoping there's a hallmark-savvy person out there who knows what the rules are in Europe! I've had a good ol' couple-hour long Google search for an answer to my question but nothing substantial has come up.
I live in FRANCE and have been selling my handmade (mainly) silver jewelry on Facebook for a little while and now a shop has asked me if I'd like to sell in their store. I have also just learned that there are strict rules about marking your jewelry (hallmark/maker's marks) if it's for sale in FRANCE.

My questions are:
1. What are the rules for hallmarking your jewelry in France - can you simply mark the silver with .925 stamp or is it done by a central agency? If so, how and where is this done!? (I've just started reading about selling in the UK and it sounds insanely complicated!)
2. What if your pieces have no flat area or are too small to mark their quality? Do you engrave it in? Is there a weight limit to what you are required to mark?

Again, bit of a long shot but I'd appreciate if anyone has any info on this! Thanks again!

MWJ