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The colors are a bit confusing. If you have a chance, could you take pictures of the stone while it's sitting on a piece of white paper? A shot more directly overhead might help too since the angle in the first picture might be causing glare (just a guess, I'm not a photographer). I want to say that it's a La Verte or a La Grise, but the dark lines on the side confuse me.
By the way, welcome to coticule.be. I hope all is well with you in your country. I would love to visit Spain some day, as part of my heritage is there.
After receiving my La Grise around noon today, I'm inclined to believe Bart. These La Grise of Regné resemble certain La Vertes too closely for me to distinguish them easily.