Yes , smilesmadly , I was speaking of the "M" & wreath as the 'central mark' .
I'm no longer a young lad , and will sometimes digress/regress into terminologies that spin around in my head , like magical pixies .
Sorry for any confusion I may have sponsored in this .
I am by no means an expert in Noritake items , I've just seen tons of it in my travels .
The Deco style of your cup was pretty popular in the U.S. for awhile , until it wasn't .
I think you may be right 'in the ballpark' about the era your little cup was made .
Others here may be able to educate us further , though .