I like 5 & 8. I'd like 5 better if there weren't the "foot" line on the top of the left half of the V. Then it would look more modern (like 6, but 6 is hard to read as a V & F), which would work for the kind of audience you're going for. 8 is also simple and easy to read, but I prefer 5.
And personally, I like the name Vulcan Forge...considering that it's jewelry, I thought immediately of the Roman god. I'm sure that, thanks to the Internet, creating an original, unclaimed name for your business would be a challenge...so if you do need/decide to change your name, good luck!