Important disclaimer: this question is not about any particular set of emojis (designed by a company or whoever else). The pictures themselves are obviously intellectual property and belong to their creators. This question is about the word emoji and whether it can constitue a trademark or not.
The story behind this question is the following: I got lost on the Internet, and discovered that the French postal services were selling emoji stamps. Nothing too interesting here, except I noticed a detail which struck me: on the website, all the occurrences of the word 'emoji' were followed by a little ®, the registered trademark symbol. I never saw this symbol associated to the word emoji before. Digging further, I discovered that the emoji stamps were produced under licence from a German company called emoji company GmbH. I don't only mean that their pictures were used for the stamps. I also mean that (apparently) they seem to claim that the concept and the trademark emoji belong to them. Their website mentions:
We are the emoji company, the owner of the official emoji® trademark. [...] emoji® is a registered trademark.
They also claim to be 'the official emoji brand' (what 'official' means here is up to you), to be the 'iconic' emoji source, and to have discovered their potential back in 2013. They do not seem to claim they are their creators, though.
It seems very strange to me that 'emoji' can be registered as a trademark. First, it is a legit Japanese word (絵文字・えもじ) meaning pictogram. Second, it's a common word of everyday language in many parts of the world, many languages, and became so presumably before the emoji brand registered it. Third, this company is not behind the spectacular expansion of emojis as a mean of expression and their internationalization (Apple and other tech companies were behind it), nor are they their creators (a Japanese guy, if I'm correct).
I did more research and discovered that the emoji company is in fact associated to various trademark agreements which allow such big companies as Sony to use the word emoji (exemple: The Emoji Movie), and various products featuring emojis (food, accessories, etc.). However, they seem to kinda mix (in a subtle way) their claim of 'emoji' being a trademark, and the IP for the icons they sell themselves.
So, are we now in a world where using the word 'emoji' without authorization is illegal? Should we really give royalties to this company whenever this word or this concept is used? Is there a strong base for their claim, or could it be challenged? And could even Apple or Facebook end up having to pay this company to provide emojis on their platforms?