~~~ which doesn't say ROYAT or even have the CI monogram under the denomination.

Is there any proof it is even from ROYAT...?

ChipGuide image.
How do we know your pearl, my pearl below or the one above is from C de R...?

We don't know... but, when a pearl has a city name on it (and without knowing what the CI is) along a CC... I'm thinking the "ROYAT CC / 100F CI" pearl is CASINO CHALET... and for one strong reason, and that's because there are a lot of CR chips that do not say too much more than a monogram and a denomination and even without a monetary unit....