how do rolex check if watch is authentic?

[cancer2]

here in manila, i brought 2 rolex watches in our rolex service center. they were so detailed in their verification. it took them almost two weeks! but they were so detailed. all parts were scrutinized, if the watch was modified, if they use genuine rolex parts, even the scratches and cracks in all parts. best of all, it cost only about 20 us dollars. how about in your areas?