Featured Art Deco Vase - Need Help with ID

Hello everyone - I am looking for help on this vase. It stands about 8 3/4". I suspect the origin is continental Europe and the style is art deco but I've been wrong before (in fact, quite a bit). Anyway, I would appreciate any help you can provide. There is a mark on the bottom but I can't make it out. There may an M in there but that's about the best I can do. The shape and colors remind me of Royal Dux but I would expect a different mark. Thanks in advance.
Don

 

Maybe try a pencil rubbing of the mark, or get something like coffee powder in it.

 

Nice vase.

For me, this search came the closest, but not there yet ...
https://www.google.com/search?hl=en...HfKuDeEQjJkEegQIAhAC&biw=1455&bih=692&dpr=1.1

Within the above is a Antiquers post with a close shape ...
https://www.antiquers.com/threads/art-deco-ceramic-vase-id-help-please.58482/

 

Looks like it says Rumrill? to me

 

Inverted, I come up with the below, mostly a bunch of numbers, BUT there's something on the left in an arc that's NOT quite readable......maybe one of you have an idea what much of it might mean??

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WOW Don, this is beautiful!
Like you, I am stumped on this one, never seen it before!

 

Just wondering, could it be older than Art Deco? Kind of has an Arts and Crafts vibe to it

 

I don't know what your pretty vase says but I am wondering if this is a letter or something.

 

Thank you all for your helpful comments. I tried the pencil rubbing and came up with what I think might 1211R M. I don't have coffee powder but I do have cocoa powder (thank you Roaring20s for the link which gave me the cocoa powder suggestion). I'll try that next and will report back if it changes anything about the mark. Thank you, Aquitaine, your manipulation of my photo was of great assistance. I looked at the vase again SIS but can't seem to find that X or crossed swords type mark. It's strange but maybe a trick of the light when I took the photo. Those dirt smudges I missed didn't help. I've given some thought to your comment, Marie. The color scheme reminds me of some Brush Pottery Cleo candlesticks I own that use roughly the same color palette. The Cleo sticks date to about 1914. Thanks, crs, for the Rumrill comment but I can't see this as one of their pieces. I think it's a bit too early and the pottery feels thinner than Rumrill. And your compliment, antidiem, is much appreciated. I won it at auction as part of a box lot over the weekend with a bunch of non-descript filthy, but intact, kitchen pitchers and thought it was too lovely not to rescue. If I missed anyone's comments I apologize. I really do appreciate everyone who comments or just looks in on my posts. Now on to try the cocoa powder!

 

I think that's a Registry number. RD then the number. That would fit with early 20th.

 

Does the back side have the little brown marks too?
I'm not sure what to think of them. I have a feeling they were never supposed to be there, but perhaps a splatter from another piece in the kiln firing hit it, and then it appears rather obvious "an artist" used a thin paintbrush with similar brown glaze and "stylized" it. What is your gut feeling about these brown marks please, Don?

 

I'm not Don, but I think the brown is the remnants of gilding.

 

The brown decoration carries over to the sides and the back in the same random pattern. It's part of the reason I thought maybe it was art deco or an attempt to make an older form appear art deco. It appears original to the vase. Some of the lines are dark brown and some tan. I tried scraping the decoration with my finger nail and it's definitely under the glaze.