This is a very pretty tea set! And a lovely example of the skills and artistry of the Noritake decorators which is what this mark tells us it is, but it was also made before the tradename "Noritake" was born (or at least the piece with that "Nippon" mark was).
The company that eventually became "Noritake" was founded in 1875 by Baron Ichizaemon Morimura VI -a mouthful of a name, I know, but a masterful businessman who came all the way round the world to sell fine china in New York and Paris, and not only overcame the language barrier selling to the "round eyes", but many other industrial and technical hurdles too, and with his brother's help, ended up creating some of the finest porcelain tableware in the world at the time (and since then, frankly) and this set is no exception. It's the Morimura brothers at their very best.
It's also quite early dating to 1891 - 1905 when the Morimura brothers called themselves Nippon Toki Kaisha Ltd. So your set is well over 100 years old and therefore officially an antique (if you take the strict definition of "antique" as being an age of 100 years or more).
We know it must be pre-1905 because that was the year when the company began using the "Noritake" brand and also the wording "Made in Japan" instead of "Nippon" which is how the country of Japan liked to style itself at the time.
The mark in the middle is the "Komaru" symbol, one of the company's earliest logos. It's a stylized version of the Japanese character
meaning "Overcoming Difficulties or Stress" referring to problems the Morimura brothers faced exporting their china to the West, overcoming the enormous barriers of language, culture, geography and industrial production. Komaru also means "Becoming Stressed" which was no doubt their secret subtext, too!
Whether this is true or not, it makes a good story, however the more prosaic explanation is that the symbol also happens to be the historic family crest of the Morimura clan.
Here's a helpful graphic of the various marks and how the Komaru symbol evolved.
I love the fact that your service contains a salt & pepper set, too. Just perfect for those cucumber sandwiches or egg sandwiches that would have been popular at "high tea" in those days. The Victorians believed that "egg without salt was like a kiss without a mustache".
Despite all this history and artistry, I'm sad to say these Art Nouveau era tea sets by Noritake are completely unappreciated by collectors because no-one knows the full story of them anymore, and the extraordinary technical skill required to make & decorate the porcelain with that raised paste gold enamel (all hand done by painters squatting on the ground, here's a Japanese decorating studio in 1904) nor does anyone entertain with fine china like they used to, so values for these sets are a joke compared to what they should be in terms of what it would cost to make the same today, that's assuming of course you could even find the skills to do so, which is highly doubtful.
Having said that, this particular pattern is quite a famous one and there is still a steady demand for it on the secondary market. The pattern is mostly known as "Christmas Ball" but also called "White and Gold" and "Rose and Tulip."
If you saw your set for sale in an antique store, it would have a full retail value of around $550. This is also the replacement value for insurance purposes.
Expect to get 30% - 40% of this if you were to sell at auction or on line (eBay etc).
I do hope this helps!
Please let me know if you'd like me to explain or expand on any of the above, I would be glad to.
PS. Thanks so much for doing the rain dance, it worked! You can stop now; my bucket rain gauge says 10" at the latest look! It certainly has dampened out all the embers thankfully, but not before destroying nearly 2000 homes in Sevier Co, TN and killing more people than they will probably ever determine, since all that's left of each home is a pile of ash turned to paste in the rain. Very sad.