The phrase "real diamond" refers to a genuine or authentic diamond, not a fake or artificial one. It means that the diamond is natural and made of actual carbon, created through geological processes deep within the Earth.
Sentences with «real diamond»
I love it, but he wants to get me a «real» ring with real diamonds before the wedding. (thecollegeinvestor.com)
They looked like real diamonds, a lil on the heavy side but nothing I can't handle. (renttherunway.com)
Real diamond watches come at all price points and in many designs. (geekwrapped.com)