If you look at the one with the smoked appearance well, you'll see that it has an interesting side view as well. The smoked part is about 6 or 7 mm thick, then follows a much paler, creamy part, and finally a BBW (it's a natural combo) that starts real purplish and gradually fades to blue.
As far as correlating properties to stone colors, I really am very careful with that. In most cases, such as this "smoked" one, I don't have any clue. Red certainly doesn't mean "fast" in my book. Thought it doesn't mean "slow" either. Nor "Medium" for that matter. I've seen red(dish) Coticules perform all over the spectrum.
There are only few morphological correlations that I'm adhering some truth to: of course we have the La Vertes. They all have a greenish hue. And the majority of them is on the slow side. But La Verte is not just a color. It's a Layer.
Then we have hones with red lines running across the surface. That mostly occurs at La Dressante, but also Les Latneuses occasionally has them. These seem to be invariably fast on water. Note that I said water, and that I said red lines.
The black manganese lines seem to predict good speed (on slurry) in most cases. And black manganese hairlines on a La Dressante usually turns out to be an amazingly fast Coticule on slurry that slows down to the finest abrasive sensation on water you've ever felt. One of my favorites.
Then there are La Grosse Blanches with brown okapi stripes, as the one I was using for the Dilucot video. Those usually have an almost soapy slurry and seem guaranteed to leave mellow edges.
But that's really about it. Other than that, I have not been able to distill much information out the appearance of a Coticule.
But they can be beautiful, that's for sure.
Best regards,
Bart.
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