How To Tell The Difference Between Diamonds and CZ?

A co-worker has a huge engagement ring that she’s trying to pass off as “real”. Right! In that it exists!

I’m just “bitchy” enough to want to know the truth. Is there any way to tell just by looking?


Hi Marsie
Apparently it’s quite difficult. According to this.


<silly answer>

Get out the Karmic Debt Scale. A diamond naturally bears a heavy karmic debt from the underpaid and unsafe labor used to pry it from the mines, the megacorporate greed that moved and sold it at far more than its proper market price, and the grease from the salesman who pressured someone into buying it as a symbol of eternal love. A cubic zirconia, on the other hand, has a much lighter load from its artifical origins - merely a slender layer of slime from a seller or buyer who tried to pass it off as more than it was.

</silly answer>

Not without magnification, most of the time. If it doesn’t have a very bright sparkle, or sparkles without a lot of prismatic spread, then it’s more likely to be a cheap (flawed and/or poorly cut) diamond than a CZ, simply because badly flawed CZ’s don’t leave the lab of their birth. But if it does sparkle well, it could be either one.

(I prefer clear topaz to either one, but I’m weird.)

Not sure if this is in the right forum, but I believe the only way you could really tell is if you looked at the “diamond” through a loupe.

Unless it’s a flawless diamond (and if it’s huge, that would cost hundreds of thousands of dollars), a real diamond would have visible inclusions which are visible through the loupe, unless it’s an inferior diamond, then you would be able to see the inclusions with the naked eye. A CZ would not have inclusions.

I have seen a very nifty little gadget used by a diamond merchant about the size of a couple of fountain pens strapped together*. He demonstrated how it could differentiate between a diamond and a CZ stone by measuring the heat reflected by the stone. Apparently, the device directed some form of heat or beam at the stone, and beeped if it was a diamond. Useful in case a thief ever tried some substitution scam in the shop I guess, as the shop wasn’t in business to buy up people’s old ‘diamond’ rings.

    • it was the gadget, not the diamond merchant which was the size of two pens.

A woman at work has a nearly perfect track record when it comes to telling the difference. Her dad and mom were jewlers so she’s got a bit of practice. For a new ring, she can simply pick up on brilliance, color, etc. clues. I thought that was bunk until I spent some time in a Tiffany’s, once you see high quality diamonds, czs are easier to detect. The real clincher for her is the setting. A cz doesn’t often come in a cheap setting.

Ack; that’s “a diamond doesn’t often come in a cheap setting.”

Diamonds are supposed to be really hard so get a hammer and smash her ring. :stuck_out_tongue:
How much did this girl say the ring is worth? A loupe will probably confirm if it’s real, as will a thermal probe, but you probably can’t get your hands on those. I tend to think CZs look really clear and glassy. I’ve also noticed more of the colour spectrum comes through, especially blue.

Here’s a way I was taught when I worked in Jewelry.
Keep in mind, however, that it works best with a loose stone.

Get a piece of white paper.
draw a straight line on it.

turn stone upside down.
run it over the line.

With a cz, you will be able to see the line clearly.
A diamond will refract (?) the light causing the line to not appear continous.

Regardless, unless you are a pro, I don’t think you will be able to do any of these methods without her knowing it. Either way, no one wins.

Cafe Society is for discussions about the arts. General Questions if for questions with factual answers. I’ll move this to General Questions for you.

Off to GQ.

DrMatrix - Moderator

Slightly off-track but still in relation to the discussion of cubic zirconia v diamons…

I read the link and all the replies about telling them apart and one thing occurred to me… if cubic zirconia and diamonds are both so hard to tell apart and for jewelry they are pretty much the same, I’m curious as to why the distinction is made at all - it’s all just about the appearance of the shiny rocks right?

Is it just about people’s emotion in regard to synthetic v natural or is there a more logical reason? (for example: diamonds are more durable)

The “logic” is from decades of media onslaught, In My Opinion.

I got a diamond tester pen, it has a real diamond tip & I run on on the face of the stone. A real diamond won’t be marked by it. There are other machines that can do it but they cost more. With a lot of experience a person might be able to tell just by looking, but I don’t think they can do it with their bare eye, you’d need a loupe.

I’ve heard people say that they would only wear a diamond because it is “real” and they refuse to wear anything “fake.” To that, I say “whatever helps you sleep at night.”

A large part of the reason is, as Uncle Bill points out, the result of decades of media onslaught by DeBeers. They are ones who pioneered the whole notion that you absolutely, positively have to have a diamond engagement ring in order for it to be “official” and that the man has to spend 2 months salary on the ring or else he is a cheap bastard who will make a lousy husband.

The “real” reason (in my opinion) is simply that real diamonds cost more than cubic zirconium (of course, the only reason they cost so much is because DeBeers is a monopoly and carefully controls the available supply, but that’s a topic for a different discussion). If cubic zirconium cost as much as real diamonds, people would be wearing them and bragging about them the same way that people brag about their diamonds. Having an expensive item, whether it is a diamond, a fur coat, a car, or whatever, makes people feel rich, privileged, and generally superior to other people. A cheap substitute – even one indistinguishable to observers, just cannot convey that same feeling of superiority to the owner. If the DeBeers monopoly ever broke up and flawless 1 ct diamonds could be had for $100, I suspect people wouldn’t really care about showing them off anymore.

For the record, when my fiancee and I got engaged we picked out a really nice setting for her engagement ring (worth hundreds of dollars) and then had a 1 ct cubic zirconium placed in the setting. Neither of us could stand the thought of paying thousands of dollars for a piece of rock (and, since we were getting married, it was “our” money being spent and not just mine). We didn’t mind paying a lot for the ring itself, since quality custom workmanship shows and is worth the price, but a cz stone looks identical to (better than, actually, since it is flawless) a diamond and it’s not like we were buying the ring as an investment. To anybody who thinks that if I really loved my fiance I would have been willing to spend $7000 (2 months salary) on her, all I can say is that the money we saved went to help pay for the wedding, the honeymoon and the down payment on the house. In other words, I did spend the money on her.

Personally, I think it’s sad that people still judge a man’s worthiness as a husband by the amount of money he is willing to waste on a piece of rock. But then, that’s just me.



Fortunately, my SO loves pearls, not diamonds. Unfortunately, she also loves emeralds.

Perhaps you are not so fortunate that your SO loves pearls.
When I worked in jewelry, we had some strands of cultured perals that would sell for way more than some diamond rings.

I think that this is because, at least currently, diamonds are an investment and CZ are not.

Granted, this may indeed be due to DeBeers, etc.

Regardless, a diamond can be worth a lot of money and sold.
A CZ, as DeBeers would put it (so take it with a grain of salt) are manufactured, so you can produce millions of them, thereby lowering their value.

Actually, my understanding is that diamonds make really lousy investments. They don’t tend to go up in value due to the large numbers available, and their resale value (i.e, to a dealer) is usually a fraction of the original price paid.

Besides, a diamond engagement ring is supposed to represent a love that lasts forever – who buys one thinking about how much they can resell it for at a later date?

I stand by what I said earlier – it’s all about what they cost and the smug sense of superiority that gives some people. Without that feeling of “I’m better than other people because I have something really expensive on my finger,” there’s really no reason to prefer a diamond over a cubic zirconium, especially since it’s nearly impossible to buy a large diamond as colorless and flawless as your average cz. Some people claim, in fact, that cz actually refracts light slightly BETTER than diamonds, making them an even better choice for those who like sparkly things.


I should rephrase that.

You are correct in that they are lousey investments.

What I was trying to say was that if you had to, the diamond could at least get you some money. The CZ will get you nothing.
Regardless of the reasons why this is so, it’s the way things are currently.

Yes, engagement rings are emotional, etc, but things do happen. If I had a kid that needed money, etc, I would have no problems selling my ring. It’s just a ring, to me.

However, it should be noted that diamonds (obviously) are not soley put into engagement rings. Maybe you have a diamond necklace that you want to sell, or trade up? We would often have people come in and trade their stones in for larger ones.

Well, it depends on how honest you are and how gullible the potential buyer is…