How do you tell if a diamond is real in a ring? I have real diamonds and cubic z rings and I can not tell by looking at them if they are different or not?
Can anyone tell me how to tell them apart for sure? Thanks so much!

A real diamond will scratch glass. There is no harder, stronger, more durable element on earth then diamonds.

If you have a UV light hold it over, the diamonds if they have fluorescence will reflect blue, the CZ's will not.
Blow on it with an open mouth, the CZ will hold the condensation longer than the diamonds.

Did the seller not given you authentication certificate from IGI or the reputable institutes? Always ask for such one.

did the seller not given you authentication certificate from IGI or the reputable institutes? always ask for such one.

It depends on the price. Also, if it shines rainbow and scratches glass, it can be proven to be diamond.