Noritake China Tea Set, Pattern #1389, Red R.C. Stamp

I came across this tea set initially knowing very little about it. I now know that it could has as old as 1926, it has the India/Southeast Asia stamp and that the red stamp is very uncommon. After a lot of searching we found that the pattern is #1389. But, we can't seem to find any information on the teapot. We have seen this pattern on other items but have yet t find another teapot. Is it uncommon?

Also, does the red stamp increase the value of these items? Approximately how much is this lit worth?

Note: one of the teacups/saucer/plates in the picture is a mismatch and does not belong.