# How To Tell The Difference Between Diamonds and CZ? **URL:** \ **Category:** Factual Questions\ **Created:** [June 16, 2003, 2:49am UTC](https://boards.straightdope.com/t/how-to-tell-the-difference-between-diamonds-and-cz/182134 "2003-06-16T02:49:17Z")\ **Posts on this page:** 10\ **Page:** 2
**Author:** ![Bad\_News\_Baboon](https://avatars.discourse-cdn.com/v4/letter/b/5fc32e/32.png) [@Bad\_News\_Baboon](https://boards.straightdope.com/u/Bad_News_Baboon)\ **Post date:** [June 16, 2003, 8:12pm UTC](https://boards.straightdope.com/t/how-to-tell-the-difference-between-diamonds-and-cz/182134/21 "2003-06-16T20:12:30Z")
Hey Barry… I have a stone I need to sell real cheap… you interested? 😉 ---
**Author:** ![Uncommon\_Sense](https://avatars.discourse-cdn.com/v4/letter/u/f9ae1b/32.png) [@Uncommon\_Sense](https://boards.straightdope.com/u/Uncommon_Sense)\ **Post date:** [June 16, 2003, 9:01pm UTC](https://boards.straightdope.com/t/how-to-tell-the-difference-between-diamonds-and-cz/182134/22 "2003-06-16T21:01:20Z")
> [@](#): > > \*Originally posted by godzillatemple \* > \*\*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.” > 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. > \*\* Your wife has no idea she`s wearing a CZ does she? 😃 ---
**Author:** ![Ferris](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ferris/32/11573_2.png) [@Ferris](https://boards.straightdope.com/u/Ferris)\ **Post date:** [June 16, 2003, 9:03pm UTC](https://boards.straightdope.com/t/how-to-tell-the-difference-between-diamonds-and-cz/182134/23 "2003-06-16T21:03:06Z")
Another thought, related to the ‘value’ of engagement rings specifically: No cite, but I recall that traditionally, in WW’s 1 & 2, quite a large number of soldiers got engaged before being posted overseas. With the possibility of them being killed before returning and being able to marry their fiancee, an engagement ring was a practical way of giving the woman something of value that could help her financially - of course in those days it was harder for women to get good jobs and/or get engaged again after a ‘certain age’. In this instance, spending two month’s salary was perfectly justified, as the man was essentially saying, “If anything happens to me, I want you to have enough money to manage.” Of course, times have changed, but I expect that it is this tradition that has been subtly hijacked by DeBeers in modern times. ---
**Author:** ![godzillatemple](https://avatars.discourse-cdn.com/v4/letter/g/49beb7/32.png) [@godzillatemple](https://boards.straightdope.com/u/godzillatemple)\ **Post date:** [June 16, 2003, 9:54pm UTC](https://boards.straightdope.com/t/how-to-tell-the-difference-between-diamonds-and-cz/182134/24 "2003-06-16T21:54:47Z")
> [@](#): > > \*Originally posted by whuckfistle \* > \*\*Your wife has no idea she`s wearing a CZ does she? > > 😃 \*\* Actually, it was her idea. She wanted something that looiked nice, but didn’t feel comfortable wearing something worth thousands of dollars. Plus, she thought it was ridiculous to spend so much money on a piece of jewelry. Barry ---
**Author:** ![Catalyst](https://avatars.discourse-cdn.com/v4/letter/c/e47774/32.png) [@Catalyst](https://boards.straightdope.com/u/Catalyst)\ **Post date:** [June 17, 2003, 1:15am UTC](https://boards.straightdope.com/t/how-to-tell-the-difference-between-diamonds-and-cz/182134/25 "2003-06-17T01:15:44Z")
I didn’t check all of the links on this page, so forgive me if it’s been mentioned already, but according to my physics teacher, CZ has an index of refraction very close to that of water; diamond doesn’t. So, if you drop your ring into a glass of water and have a hard time seeing the stone, you’ve got CZ. Unfortunately, I don’t have any way to verify this myself. ---
**Author:** ![Cardinal](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cardinal/32/4000_2.png) [@Cardinal](https://boards.straightdope.com/u/Cardinal)\ **Post date:** [June 17, 2003, 2:33am UTC](https://boards.straightdope.com/t/how-to-tell-the-difference-between-diamonds-and-cz/182134/26 "2003-06-17T02:33:17Z")
Yeah, that “two months salary” thing really makes me laugh. I would NEVER spend that much, no matter how much I made. Even at a minumum, there’s absolutely no way I’m spending $5K on a ring. You must be on crack. This would actually be an issue that could torpedo a relationship, for me. If she insisted on something even remotely like that, we’re not compatible about resources and money. ---
**Author:** ![Glassy](https://avatars.discourse-cdn.com/v4/letter/g/ea666f/32.png) [@Glassy](https://boards.straightdope.com/u/Glassy)\ **Post date:** [June 17, 2003, 3:59am UTC](https://boards.straightdope.com/t/how-to-tell-the-difference-between-diamonds-and-cz/182134/27 "2003-06-17T03:59:56Z")
Actually, I have a related question that I hope some of you savvy dopers will help me with. (Marsie, I hope you forgive this semi-hijack: it’s related, I swear.) My great-grandma left me a rather ugly diamond ring; when I was getting married I decided to have the stone re-set in an attractive setting, and use as my engagement ring. I went to a jeweler to have it re-set. She had an electronic instrument that looked like a pen, attached by a cord to some kind of little box. She demonstrated it to me: when she pressed the pen to my grandma’s diamond, it beeped. “That means it’s real,” she said. Then she picked out a CZ ring and pressed the pen to it: no beep. I left the diamond with her for about a week to have it set, and when I came back in, she pressed the pen-device to my new ring, and it beeped. This was to show me that she had actually put my grandma’s stone in the ring, and hadn’t replaced it with some cheap CZ. (Because empirically I have absolutely no way of knowing the difference.) However, it would be totally easy for her to con me using the “mysterious device that beeps according to some principle that I don’t know about” method. I don’t actually suspect her of stealing my grandma’s diamond from me, but I’m not sure if I’m falling for the beeping-pen gambit, either. Anyone familiar with this device? Thanks in advance. ---
**Author:** ![Cillasi](https://avatars.discourse-cdn.com/v4/letter/c/71e660/32.png) [@Cillasi](https://boards.straightdope.com/u/Cillasi)\ **Post date:** [June 17, 2003, 4:08am UTC](https://boards.straightdope.com/t/how-to-tell-the-difference-between-diamonds-and-cz/182134/28 "2003-06-17T04:08:14Z")
The difference between diamond and cubic zirconia is like the difference between glacier ice (classified as a mineral) and an ice cube. Both diamond and cubic zirconia are carbon-based crystal lattices (I think), but diamonds formed naturally under tremendous heat and pressure within the earth (natural) and cubic zirconia is manufactured (artificial). ---
**Author:** ![Truth\_Seeker](https://avatars.discourse-cdn.com/v4/letter/t/5fc32e/32.png) [@Truth\_Seeker](https://boards.straightdope.com/u/Truth_Seeker)\ **Post date:** [June 17, 2003, 7:41am UTC](https://boards.straightdope.com/t/how-to-tell-the-difference-between-diamonds-and-cz/182134/29 "2003-06-17T07:41:33Z")
> [@](#): > > \*\*Both diamond and cubic zirconia are carbon-based crystal lattices (I think) \*\* False. Cubic Zirconia is Zirconium oxide. It has, apparently, been found in nature (rarely) but as a practical matter, the entire world supply is manufactured. They are extremely difficult to tell apart from diamonds with the naked eye. > [@](#): > > \*\* To the untrained eye, cubic zirconia looks identical to a good quality diamond, but CZ has slightly less brilliance or sparkle than a diamond and more fire or flashes of color. The overall effect is so similar that it can even fool a trained gemologist on occasion. One great difference between cubic zirconia and diamond is weight; CZ is about 75% heavier than diamond. A piece of CZ the same size as a one carat diamond weighs about 1.75 carats. CZ is also more brittle than diamond and softer. ([bodyjewels.net](http://bodyjewels.net)) Cubic Zirconia is also flawless, whereas diamond usually contains impurities and inclusions. \*\* [http://www.emporia.edu/earthsci/amber/go340/students/berg/cz.html](http://www.emporia.edu/earthsci/amber/go340/students/berg/cz.html) The “pen with the cord” or the “two pens taped together” is a [diamond tester.](http://www.gemworld.com/DiamondTesters.asp) The basic ones work by measuring how fast heat difuses – diamonds have an extremely high thermal conductivity, much higher than CZ. The latest diamond simulant, moissanite, can fool one of these detectors so the fancier ones include another test (I believe it’s an electrical conductivity test) that can tell diamond and moissanite apart. This isn’t really necessary, though, because, unlike diamond, moissanite is doubly refractive so that it’s pretty obvious with a loupe on anything but the smallest stones. Anyway, for good sized stones, you can tell accurately enough for office gossip with just a loupe. If it’s doubly refractive, its moissanite. If it’s flawless, it’s almost certainly not diamond (though an adept goldsmith will often use the mounting to hide flaws). By the way, you can’t necessarily tell from looking at the mounting. If it is a cheap mounting, it’s almost certainly CZ. However, if it’s an expensive mounting, it still may be CZ. You can buy CZ rings that cost several hundreds or even a few thousand dollars. In fact, it’s fairly common for people who have jewelry with really large diamonds to have a copy made in CZ. The real diamond stays in the bank vault and the person keeps the copy at home to wear. ---
**Author:** ![Urban\_Ranger](https://avatars.discourse-cdn.com/v4/letter/u/e9c0ed/32.png) [@Urban\_Ranger](https://boards.straightdope.com/u/Urban_Ranger)\ **Post date:** [June 17, 2003, 11:25am UTC](https://boards.straightdope.com/t/how-to-tell-the-difference-between-diamonds-and-cz/182134/30 "2003-06-17T11:25:26Z")
> [@](#): > > \*Originally posted by Bad News Baboon \* > When I worked in jewelry, we had some strands of cultured perals that would sell for way more than some diamond rings. Argh! Don’t give her any ideas! ::looks around Too late! [Previous page](https://boards.straightdope.com/t/how-to-tell-the-difference-between-diamonds-and-cz/182134.md?page=1)