this is a very interesting piece, ive had it a few months myself, not seen one like it before, it looks to be made from some kind of hardstone, it looks like it might be some type of jade, it measures about 11cm across the base seal and about 9cm across the top, 4.5cm high, and it weighs about 1.5kg which is very heavy for its size. it has unusual character marks / symbols on the top and bottom, also has decoration around the sides which is hard to see unless you hold it in certain light. could turn out to be a very rare and collectable piece as it came from a good private collection i bought last year. please enlarge all 20 photos and read condition report as it does have lots of imperfections, cracks, sight losses. but still a very solid heavy well made seal.