(1) Wear a diamond on your arm or face. If it feels warm, it is a fake diamond. Because real stones don't transfer heat, no matter how you touch them, they should be cold.

(2) Breathe into the diamond. If the water vapor on the diamond disappears immediately, it proves to be a real diamond. If the water vapor stays on the diamond for a few seconds and then disappears, it is a fake diamond.

(3) Draw a straight line on a piece of white paper, put the diamond flat on this straight line, and observe this straight line through the diamond. If the lines at both ends of the diamond edge and the lines passing through the diamond are broken or deformed, it can be concluded that it is a real diamond, and if the lines are still straight, it is a fake diamond.

(4) Rub the diamond back and forth several times on fine sandpaper. Those with scratches on the surface are fake diamonds, while those without scratches are real diamonds.

I just saw these, too I don't know if they are useful to you, but they must have some authoritative certificates. I also want to buy diamonds. Just learning to communicate.