Second, look at the hardness. Sterling silver is soft, and you can probably know the hardness by gently breaking it. Or scratch it gently with a needle to see if there are any marks.
Third, look at the color. The purer the pure silver, the brighter it is. You can also judge the truth by looking at the color. But some old models are hard to see.
Fourth, blacken the bracelets and wash them white. It must be true if it can be blackened and washed white. (You can use the bubbles of sulfur soap to turn black. Fifth, burn it with fire, and the more it burns, the whiter it is.