Go to the image section of your search engine and type in argand and astal lamp shades. It should look vaguely familiar. Some are made without fitters on the bottom and I'm enclosing a link below to show a pair similar to yours. They were often quite beautiful and predated kerosene lamps and many burnt whale oil. See what you think.

Here is a link that might be useful: argand lamp shades

I'm wondering if it wasn't part of a oil lamp. The bottom sat in a ring held in place by fingers that kept it from moving about.
The reason you may not be seeing many is they were delicate and often were either dropped and broke or cracked if the wick wasn't kept trimmed.

Thanks for the link. I've looked at many shades for argands & astrals in my searches but yours is the first that I've seen with a flat bottom; most look like they have a straight sided shaft that fits around the burner. Some strange shapes, too! Would a company register a patent on a shade in 1898 for a type lamp that had been outdated for years?

I've heard there are sites for old patents online, and in fact I've run across some of them accidentally but never really searched for any. I was most impressed with the shapes of the chimneys for the astral and argand lamps. Many were quite lovely and decorated like yours and some with very small flutes at the top. One site (and it may have been the one I linked to) had seperate sections for shades and it might be productive to access that and send an email in to an expert on old lumanaries and you might hit pay dirt.

It's so lovely, you can tell I am intrigued. I've never seen anything quite like it.

The astrals & argands are something special, aren't they?

Funny thing is that I'd pretty much forgotten about my shades until Palimpsest posted a question a while back about argand lamps in the Antiques forum & that jogged my memory to bring them out & do research. I vaguely remember buying them at auction in the early 70's & I'm sure the only reason I could afford them was because one had a chunk gone out of the ruffle - & I still had to beat out a few other bidders.