Time frame mostly.
The Mckinley Tariff act of 1890 stated that imported items needed to be labeled with the country of origin...
Japanese goode were often labeled Nippon or Nihon...which is Japanese for Japan....then in about 1920 a law was passed that things had to be labeled with the country of origin in English....which led to "japan"...and later to "made in Japan".
It's nor a hard and fast timeline...just a general indication.
You will see china marked "hand painted Nippon" which tells you it was made after 1890 but before 1920. IF it's not a faked label. I have actually seen rolls of peel and stick labels with the RS Prussia green mark on....meant to be applied to unmarked china to fool the unwary.
Linda C

I have a couple of things that have "Made in Occupied Japan" which was the required label immediately post-WW2. I believe this was '45-'52. The printing appears to be glazed on and they were childhood gifts during that timeframe so I think they are genuine.

During the allied occupation of Japan, items for export had to be labeled occupied japan...time frame was as luckygal said.

These are horse head salt/peppers. Just the word Japan on the bottom. So likely after 1920 but before 1945? I don't need an exact date, just had bought them because I liked them and then wondered how old they were. Thanks for the info.

In the late 1960's there was a big controversy regarding some Japanese products, mostly cheap electronics, that were labeled "Made in USA". When the controversy first broke it was argued that the manufacturers had intentionally perpetrated a fraud, but it was later proved in court that after the war one of Japans coastal manufacturing cities had actually been renamed Usa, Japan and the products had been made in the City of USA, Japan.

I remember the incident vividly because I personally had a 6 transistor AM pocket radio that was marked "Made in USA" in raised letters on the exterior of the plastic case but when you opened the battery compartment there was a paper label that said "Made in USA, Japan"

For a short period after that many manufacturers in the US made a point of inserting periods between the letters so their labels read "Made in U.S.A."

The S&P set is pottery type stuff. Feels old. Looks old. But no matter. I like it.
Interesting about the Usa, Japan. I don't remember that. I've been wondering what ever became of my pocket transistor radio. I suppose like everything else that I can't find, it's gone somewhere. If I ever find it all I'll need a warehouse to store it in.

I think Lazypup took your transistor radio and threw it in an agitating washing machine at Sears as a prank... Sorry Lazypup, I am STILL loving your octopus story!!!!!

Please I want to know if the tiny delicate white teacup s, with saucers marked Japan with gold trim are worth money.

There are many white teacups that are marked Japan. Without a picture impossible to tell but probably only what someone would want to pay you.

How old are they

What yr did they start marking made in Japan with stickers?