Why did Andy Lau do a little magic trick?

1. Hold the ring with the thumb and forefinger of the right hand, and gently press the middle finger against the bottom of the silver ring. 2. When the right hand is released, the ring will be turned over in the air due to the pulling of the middle finger, and it will be vertically inserted into the inside of the necklace. Tip: the neck chain must be fixed enough, and swinging from side to side will fail; The thumb and forefinger of the right hand hold both sides of the ring, and the middle finger leans slightly on the bottom of the silver ring, which is not easy for the audience to notice. Let go of the right hand, because the middle finger holds it, you can successfully make the silver ring slide vertically. Note: the middle finger is used to pave the way for the ring to fall off (the ring falls off after turning it twice on the chain)