The one in the OP, not so clear....I can see a bit of the lower right curve of the oval on the 'cartouche' on the right, and what appears to be Glyphs inside, but the details are difficult to make out.
Photobucket leaves something to be desired, and it's not saving the enlarged pic, maybe you can take it from here, (editing pics are not my best skill).
Campbell's Chamber roof blocks are Tura Limestone until proven otherwise.
THE Cartouche in Campbell's Chamber IS Authentic, as are ALL other RC's Glyphs, until proven otherwise.
"This Forgery 'theory' has more holes than a sieve basket."