This thing is small enough that it might just fit inside a spinning magnetometer. This device can document the magnetic strength and direction of the specimen without harm.
If you wanted to discover more about the magnetic signal, minerals, temperture of signal, etc, it would require heating the specimen in stages and reading the signal at each stage. That would, however, destroy the magnetic signal of the rock.
The surface should be examined to determine if the specimen was carved or molded. A look through the microscope should have provided some clues: are the grains broken or not? A look through a Scanning Electron Microscope could make that very clear.
Have it x-rayed.
To me, the object looks molded and kiln dried, not carved. The cracks would be from the drying in the kiln.
Just because it is hard, and not typically used for carving, does not mean it cannot be carved. Jade is very, very hard material but is often carved.
Why does it look like a circle from years ago? 'Cause the hoaxster copied it from an image of that circle when they made the object. If they made one, they may have made more, and planted them in other places as well.