Looks like a signet ring for sealing wax. My French is nonexistent, but it looks like they do not know anything about it in terms of meaning, original use, original owner, the purpose of the seal, etc. I know nothing about this kind of thing, but the design does not appear to be ornate for the purpose of its owner. Rather, it appears the effort went into the appearance of the seal it signs. If those assumptions are correct, it makes this ring an interesting case of gold as a utilitarian functional object and not intended for direct ornamentation.
It is not all that unlike right now. The silicon chip packaging for most chips inside the device you are looking at right now has tiny gold wires between the die and every connection into and out of the packaging; serving a functional purpose not intended for ornamentation.
I mean, yeah, money is utilitarian too and at times made with gold, but IMO, money usually does not have a personal connection like a worn ring or personal device. I picture a ring like this being a job of some mid level bureaucrat, or some prominent family item.