This intriguing stone has been found by Joshua Pollard (University of Southampton) and his team during fieldwork on a site called Kellah Burn, in Northumberland, UK. The stone seems to have been initially used as a quern. Afterwards, the quern was decorated with this beautiful wavy motif. David Wheatley and I have applied RTI to see if the technique revealed more details of the surface of the stone than the ones seen by direct visual inspection, and also to facilitate its interactive visualization. If you click on the image you will see how the RTI specular enhancement reveals various interesting details that are not visible in the normal photograph.