Chow Tai Fook TMARK Seal applies the exclusive patented nano-machining technology, so that the diamond can maintain the quality of 100%, without any etching damage and chemical residue. The size of the imprint is only 5 nanometers, which is the smallest diamond imprint in the world at present. It is 10 times thinner than the common mark on the market, which is equivalent to one twentieth of the thickness of a piece of white paper, and it especially retains the original dazzling refraction of diamonds. In order to achieve all this, TMARK adopts the world-leading top patented technology, thus making this extremely fine nano-imprint perfect. Under each T mark, there is a unique number.