It may not be entirely accurate but they'd probably be listed online as "Eastlake" style. They are very cool! are you sure they aren't bronze?

Not sure if you're looking for antique/salvage or replicas to replace them, but have you checked House of Antique Hardware? If you don't want replicas, the terms they use to describe the replicas could help guide your salvage search. That would also give you an idea of the period so you could look for a less fancy/expensive but still period-appropriate replacement. Happy hunting!

I agree with @Fori, the knobs would probably be lumped in the “Eastlake” category in terms of style. Why do you think they are ceramic? They are most likely cast bronze. Scroll through the antique knobs on The Brass Knob website - many of the knobs are identified by style/pattern and/or manufacturer - maybe give them a call and see if they can help. Even if you don’t find what you are looking for you’ll have another search tool to add to the one suggested by @Libby Estell.

Edited to add Olde Good Things - another website with lots of antique knobs.

Check out Liz's Hardware as they have a huge stock of vintage hardware of all styles and from all periods. I extensively search for antique hardware and tried House of Antique Hardware but ultimately found what I needed Liz's.

Liz'a Antique Hardware

They have a website but their actual inventory is far more extensive so you can email a picture

Libby thank you for the link to House of Antique. I have a waterfall buffet that I replaced the handles and the site has ones that match the originals.

Try taking a good head-on photo, and doing a reverse-image google search?

That appears like a metal knob. If so, it may be two stamped shells fastened together by edge rolling. The back shell may be roll formed. If it is a solid ceramic, it will have tell-tale weight. Those old solid knobs weighed 2 to 3 times more than a hollow metal one.

Gothic. The vines/leaves are too representational to be Eastlake.

("Eastlake" is for googling, not for identifying actual style. :P )

Can you scratch an inconspicuous spot a little to see if it's metal? They might be brass.

Try an image search for 'antique victorian brass door knob' maybe?

This may seem weird, but I often tap my teeth against things to determine what they're made of. Glass, ceramic, metal and plastic all feel very different.

Thank you all for your input. Through some extensive internet searching, my hero husband found a russell and erwin catalog from 1875 that has the knobs. The are from a line called 'Lava' and the style is Gothic. They are some kind of wood based resin material and, even knowing exactly what they are, still pretty difficult to find. We found 3 knobs on Ebay but we need a total of 16 to replace all the missing ones in our house. It would be nice to find a few more as well because some of the remaining ones we have are pretty abused. We will definitely check out
Liz'a Antique Hardware. If we can't find enough of them, we plan to look into replicas. I've heard good things about House of Antique Hardware. Thanks again!

This patent can be seen at the link below:

Door Knob Patent, dated Nov. 2, 1869

An excerpt from this patent reads: "The design is intended to be used in the ornamentation of door-knobs and roses formed from a plastic material in moulds under pressure."

Apparently, this is a "design patent". It does not cover the door knob, but pertains to the design of the decoration for molded door knobs and roses. Note that it states, molded of plastic. This is an early patent and the material would have been an early plastic, very likely a thermoset, the same stuff that was used for pot lid knobs, pot handles, and insulating handles for electrical gear.

One such material was 'Bakelite' with the chemical name of Phenol formaldehyde, A.K.A. phenolic. However, Bakelite was not available in 1869. Bakelite was developed by Leo Baekeland in 1907 in New York, and patented in 1909. Therefore, if your knob is Bakelite, it was made after 1909.

If your knob predates 1909, it is truly an antique and representative of very early use of molded plastic. Apparently, your molded knob is quite old and that may explain why only a few exist today.

Typically, parts were not made of pure resin, but rather, the resin was filled (mixed) with fibers. Cellulose may have been one of the fillers, one source being wood fibers. Another filler is fiber-glass for strength. A colorant may have been included, usually a dark color to even the appearance and protect the resin from UV rays.

Very cool. Glad you found them, even if you can't find all of them!

Carol, you aren't the only one. And pearls. Don't forget the tooth test on pearls. :P

Dates of plastic manufacturing events are found in the link below:

A History of Plastics

The use of plastic goes back as far as 1284 using tortoiseshell as a natural plastic. However, advances did not accelerate until 1820's. In 1872, the Hyatt brothers patented the first injection moulding machine. This would mark the beginning of mass production of injection molded plastic parts, and this date fits with your 1880 date for your molded door knobs. If your knobs were made in this time frame, these would represent the cutting edge of parts-making in 1880.

This is really interesting and exciting information! Thank you for sharing.

Here's some more info I found online.

This knob set was manufactured by Russell & Erwin and has a patent date of 1869. Made of gutta percha, a resinous mixture obtained from Malaysian trees, it was one of the first plastics used in manufacturing. With the advent of Bakelite in the early 1900s, however, gutta percha fell out of favor. This particular knob set is part of Russell & Erwin’s “Gothic” pattern from their “Lava line” of hardware.

Are they still sturdy? If they are showing any degradation, I'd probably set them aside and find a similar style in metal for actual use.

I wonder how many knobs of that material are still around and kicking. Antique plastic doorknobs! Fabulous!

Another molded doorknob material had the trade name of Hemacite. Don't be creeped out, they were made from animal blood. https://en.wikipedia.org/wiki/Hemacite

I’m happy you’ve turned up some more knobs for your house. Great use of primary source materials!

Fori - yes, they are still sturdy. A few of them are showing some wear and tear. Sombreuil - Wow, I have never heard of hemacite! We recently found a bunch of knobs and roses through ebay. We lucked out by asking two sellers if they had more knobs in their collection.

We started installing a few knobs. Still on the hunt for roses that will fit.

Looks like something that could be replicated by molding or 3D printing.

Have you set up an automated notification on ebay? It might take you awhile but if you found 3, more will show up eventually. These things take time.

I found this set, wondered if you might have possibly missed it?

https://www.ebay.com/itm/352238230705

eta: Another!

http://www.historichomehardware.com/store/mid-1800s-gutta-purcha-doorknobs-and-rosettes-set-p-675.html

Thanks, Pennydesign! It's definitely a labor of love but it's getting there little by little. Thanks for the tip for closets. Voila, thanks for checking for us! We had seen those but haven't pulled the trigger as they don't have roses and we are in need of those more than the knobs themselves right now.