What scale does gold use to weigh weight, the unit is accurate? What do they use to use their professionalism and how to ensure that they will not be lacked less than two?

The price of silver jewelry in Tmall Mall is high, low, hundreds of pieces of high, or dozens of lows. Does this mean how much the silver content determines its price? Why are some shops sold on the surface of the shops very shiny? Is it fake?