Hi
The only people who can authenticate a real diamond are certified gemologists specializing in jewelry. However, if you are browsing rings at a flea market and want to quickly assess whether a clear stone is probably glass, cubic zirconium, quartz, or leaded crystal, there are a few easy tests you can apply without any special equipment. These tests at least rule out recognizable imposters because they rely on the way a real diamond stone refracts light, conducts heat, and looks up-close.
Thanks