To the average person, cubic zirconia may be indistinguishable to the naked eye. Like most things, it depends on the quality of manufacture whether it can be easily spotted. It is often very easy to spot due to the prongs and the mounting which are of much inferior quality and especially in larger stones, not nearly as numerous as would be used for a more valuable stone. To a jeweler, it is very easy to tell the difference with a microscope or jeweler's eyepiece.

No it is not indistinguishable. If you have been trained in what to look for you can easily spot the differences in color and clarity and other physical features. However if you are not trained you can be easily fooled as I'm sure many unsuspecting people have been.

Well, it all depends on the cz quality. I have seen a hand-cut Sitaragem and I had a really hard time telling the differnce. Without magnification or other tools, at first glance it looked like a natural diamond. Also, when the stone is mounted in solid gold, it makes it all the more difficult to tell. With other cz's that I encountered, you could tell right away that they were not diamonds. poorly cut and the facets were off.

No. Cubic Zirconia is slightly less brillient than diamond. Cubic Zirconia also has a higher specific gravity and density than diamond. This means that even if all other appearances were indistinguisable from a natural diamond, then you could tell the difference between the two by size and weight: for the same size stone, the Cubic Zirconia will be 75% heavier than a diamond. So if the diamond weighed 1 carat, the Cubic Zirconia stone would weigh 1.75 carats. However, to the layman the quickest and easiest test is to understand the relationship between the 4 C's (Color, Cut, Clarity, and Carat) and the market price. If the "diamond" is flawless (no visible inclusions or internal flaws with a jewelers loop) then the "diamond" is suspect, as this would be a much rarer diamond. Especially if it's being offered for significantly less than expected market value. Visit several reputable jewelry stores and tell them you are shopping for diamonds and you want would like them to teach you about what to look for. Ask them about CZ vs. diamond. It's not as difficult as you would expect, once you know what you're looking for. See: http://www.emporia.edu/earthsci/amber/go340/students/berg/cz.html

No. Real diamonds nearly all contain flaws, which make the light refract from them in unique patterns, and they also tend to contain a color. Cubic Zirconia is perfect and the color is perfectly clear. Since it's so cheap people tend to buy really honking big rings. So when you see an absolutely flawless huge stone you can be pretty sure it's fake.

I understand that natural diamonds (not created) now must have a number incised on them which is visible only with a loup.

It's not true! Wanna buy a nice 3 ct. diamond?

I'm no expert, but I am wearing a cubic zirconia ring right now until we can get my (lost) diamond replaced and I get HUGE complements on it ALL the time! "Oh what a pretty ring" "I really like that ring" so on and so forth. I know a guy who gave his wife a cubic zirconia in an expensive setting and didn't tell her. She wore it for years without telling the difference and he JUST finally bought her the real diamond for it.

If you turn a CZ of upside down, and let the table rest over a printed letter, like e, you will be able to read the letter, even if it's a little blurry. Due to the light refracting property of a diamond, you can't even see the shadow of a letter through the table. It's a quick test for on the spot assessment. Try it :-)

Nope.

No. A hardness test will reveal a diamond from a Cubic Zirconium. Diamonds are a 10, while CZ's are an 8. A quality tungsten carbide drill bit that you can get at any hardware store is a 9, so even a layperson can do such a test.

You can indeed tell they are not real, what you want are these diamonds. http://www.apollodiamond.com/ http://www.gemesis.com/ These are cultured diamonds, meaning man made, they 100% diamonds, in fact they are flawless, better then the real thing so to speak, because in fact they are the real thing, just made perfect by man. Btw they cost alot less as well.

How could it be? If they were, we wouldn't have Cubic Zirconia's. They would never have been discovered.