Two stamps. Clearly, the newer stamp is meant to indicate that the metal is 95 percent tin, which is safe. Even today, copper cookware lined with tin. (Also, I have learned that "Etain" is French for "Pewter.") The other stamp reads "Block Zinn 1791" (or 1794.) But this does not necessarily mean that the item was made in 1794. That could be merely the year that the company was established.

Any insights into when this was made and/or how to determine lead content of the metal would be gratefully received.

Broader view of the back.

Stupid dinner party question here: I don't use chargers but don't they go under the plate that you actually eat on so they can be as toxic as can be and not ruin dinner?

Or are you wanting to just use it as a really big plate (which I totally get)?

I would assume both stamps are accurate; the one with the company logo has a date of something or other in the company's history and they just didn't get that mark on there very good. But I think they were both applied at the same.
time.

If 95% tin is good enough to eat off of, I wouldn't have a problem with trusting that mark.

You guessed correctly. I DO want to use it as a really big plate. Being metal, it won't shatter to the floor if my cat performs a "gravity check" and gently nudges it from a table or counter-top. (I have a collection of brass and copper drinking vessels for this reason. lol)

Unsure if "%95 Tin" means that the lead content is low enough to be safe for eating. I would like to hear that the lead content is zero, which I understand is true for recent pieces. Thus, I was hoping someone might be able to put a fine point on its age.

Hardware stores sell lead test kits. They're mostly for use on paint, but they would probably work on the plate.