Only some physical testing would tell you for sure, but it's not impossible. There was a company in New York that supplied slabs of this material as kitchen worktops and such. It was said to be a natural breccia, although I don't know where it was sourced from.
I could well believe that the dull interior of your piece would come up as that vibrant external colour after polishing and without any dyeing. It might well be a broken piece from a slab of similar material to the above that had been cut and polished for a worktop.
One test you can try is to break a small bit off and heat it with a torch to test for resin being a binder. There are some ceramic type's of similar material but by and large artificial masonry is bound by resin.