The first should be inscribed with wood piece or broken pottery, they were stamped on th…

第二类为出土秦陶器上的抑印陶文，应当为制陶工人的私印。

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It is monochrome, with an extremely subtle pattern, and does not have a mark translating as "valuable Ding bowl" stamped on the bottom, making it look like a bowl found in Pottery Barn (and more commonly found at yard sales).

CNN: How to hunt for your own $2.2 million Ding bowl