As you look at your ring, earrings, or other piece of jewelry, you may find yourself wondering whether or not the diamond in your item is real. This may be because of the price you paid for your jewelry, because of the person who gave you the item, or for a number of different reasons. But, there are a number of tests that you can conduct to tell the difference between genuine diamond and a cubic zirconia.The first test many people want to conduct is the “scratch test.” A time old tradition, this test is not as accurate as it once was. While a diamond can scratch glass, modern technology has proven that so can some quality cubic zirconias. In addition, this test may cause you to damage your diamond, and if it’s real, will lower the value of the diamond and decrease its external beauty.
Therefore, the first real test that you should try is the transparency test. You cannot clearly read through diamonds so if you can do so on a newspaper or other type of print, then the item is not a real diamond. Though this test works with some jewelry, it is best in circumstances when you have a loose diamond. Furthermore, any real diamond that has been cut too shallow may be easy to read through and provide inconclusive results. If you are unsure of the results, you should proceed to the next test. The more tests you do, the more likely your results will be as accurate as possible.
The next test, which is similar to the transparency test, is the fog test. A genuine diamond will not hold heat. This test can be done with your breath by breathing on it like you would a mirror. If it stays foggy, it is not a real diamond. If it does not and it allows the heat to be dispersed and clear up, then it is real.
Before you conduct this test, your best bet is to make sure that your ring is clean. There are several ways that you can clean your diamond in your own home to remove any dirt or natural oils form your ring. Then you can proceed with the test.
If you have the equipment available, another test that you can conduct is the weight test. It is well known that a cubic zirconia weighs more that a genuine diamond. In fact, it weighs almost double what a real diamond weighs and therefore will tip the scales accordingly. For those who believe that their diamond is real, a cubic zirconia can be purchased of the same size, including shape and dimension, and place both items on a gram scale to see which way it tips. The important factor here is to get an item as similar as possible for the best results.
Again, if you have the equipment available, another test that you can conduct to determine if you have a genuine diamond is an ultraviolet test. A U.V. test can be applied because almost all cubic zirconia will not provide the same fluorescence color.
A genuine diamond, however, may give off a strong blue fluorescence when held under a black light. Unfortunately, the bluer hue you get, the less valuable your diamond, which means that a real diamond that shows a lack of blue may be considered a fake. If you suspect that you have a higher quality diamond and that is why you are not seeing the blue fluorescence, then other tests should be completed.
One last test you can try is the loop test, which can be conducted with a magnifying glass. This test will inspect specific characteristics about the stone, including how the facets are joined at the top of the stone and the appearance of the girdle. If the girdle is frosty, it is likely a diamond, but if it is waxy and slick, then it is likely a fake diamond. Additionally, you can look and see if the stone is stamped with a “C.Z.” on the interior of the ring, which would obviously indicate that it is not real.
Although these tests are often used to tell the difference between a genuine diamond and a cubic zirconia, not all of them are fool proof so the results could be a little confusing to determine the real from the fake. Therefore, if you have any doubt about your diamond, you can try any of these tests.
However, before you make any decisions based on your results, you should speak with a professional. Even as an imposter, a cubic zirocnia can still provide a wonderful piece of jewelry. A professional jeweler will easily and quickly be able to tell you whether or not the stone that you have is a real diamond or just a beautiful imitation.
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April 22nd, 2009 at 6:01 pm
I will say it is not a comment but a question.I have an inherited stone but I am suspecting it could be a real diamond.The stone display high rainbow colour under white light.It has an engraving of the tower of london.It has a name printed on the surface.It is higly transparent.When I viewed with under a powerful magnifying loop 10x there is not impurity or vivid thing.Very strong an d disperse light to a very far distance.shows complete rainbow refraction but it got scrached with dry sandpaper.please anybody that know about it should get back pls.
June 18th, 2009 at 5:00 pm
Real diamonds don’t usually reflect light unless they are low quality. Most diamonds have some imperfetions and scratches. Diamonds don’t usally get scratched easily, if the stone is taller or wider than 1 cm it’s prbably fake
June 23rd, 2009 at 9:20 pm
Sorry Bakare, but it’s not a real stone. Diamonds don’t have rainbow reflections and they can’t get scratched by almost anything.
August 30th, 2009 at 2:31 pm
I have a ring that has a pink stone. It’s not clear and is set in gold with lots of stamps on it. I did take it to someone but they said it was only worth a very small amount of money. I’m not convinced because of the gold it is set in. The ring is quite old but I guess that doesn’t have to mean anything! Any advice please?
September 27th, 2009 at 1:22 am
I have recently obtained what I believe to be a diamond. But I am not sure it is. I did the transparency test to check but I’m not quite sure. I tried scratching it hard on the pavement of my side walk and it got only one tiny little scratch. So I’m still unsure
December 20th, 2009 at 6:28 pm
To the Dudeness:
I can barely believe You’d consider, let alone commit the act of taking what You believe to be a real diamond & scratching it hard on the side-walk.
Is that even a recognized test ?
Besides what will it tell You ? Other than Your stone is harder than the side-walk & even then, it’s not like this is some sort a full proof test! Is it?
If it’s a recognized test then My bad.
Xproject187@Gmail.com
After all the fact that
January 18th, 2010 at 2:15 pm
Do cz’s turn blue in sunlight like real diamonds?? If so, why would the large center stone turn blue and the little channel set sidestones not turn blue?
I have a stone I thought was a cubic zirconia. It is nicely cut and does not retain fog during the fog test. The curious thing is that it turns an obvious powder blue in sunlight, the stronger and more direct the sunlight, the bluer it is. the other small cz sidestones do not do this. The blue is not present in regular incandescent indoor lighting. I do not have access to a blue light but have read sunlight does the same thing. It does seem a little darker than another cz I have, but I believe it’s due to a darker natural color, its nice cut, and the setting which blocks some light.
April 29th, 2010 at 12:28 pm
another very easy way to decipher is by using en eye loop or magnifying glass. Be sure the stone is well cleaned with no dirt or residue on the outside of it. If the stone is in a ring, turn it so you can view the stone from the underside.If there are any inclusions – pepper looking spots or white feathers or lines- it is most likely a diamond. Inclusions are natures finger print. CZs do not have inclusions.
August 30th, 2010 at 6:27 pm
I found a diamond looking earing in a parking lot. Other people may believe it is fake but I do not know. We matched it up against a real diamond and they look absolutely the same. I grinded it against red brick and jagged stone and it will not scratch. I will not hold heat unless it has oil on it(oily fingures)-it clears up in about 5 seconds. its brilliantly cut and very very small. newspaper test passed, it is not transparent.
September 12th, 2010 at 11:17 am
I recently picked up a stone and I want to know if its a diamont or not is there any test one can do the newspaper test will not work because its very foggy I scratched against my window with the stone and it made a defenate cut and I took a nail file and nothing happened to the stone but the file is blunt now.
November 8th, 2010 at 2:00 pm
@Melody-
You may have a white sapphire. My engagement ring is one, and while in most lights it’s a clear, white stone, it’s obviously slightly blue in direct sunlight.
November 25th, 2010 at 10:43 am
There is a lot of “how to tell a genuine diamond” info on the web, but most of these tests require experience. The “fog test” is dependent on the stones being at room temp., if you heat a cz the fog will dissipate very fast, a lot of diamond substitutes will clear fast. The ” frosted girdle”, a lot of imitation diamonds can have a frosted girdle, on a diamond the girdle has bearding and some diamonds have a faceted, polished girdle. Precious metal settings do not guarantee a genuine gem either in modern or antique jewels. The read-through test depends on the cut. The loupe examination depends upon knowing what inclusions look like in a diamond, many fake stones also have “inclusions”. Thermal conductance testers are good when used properly. UV light test can be good also and can sometimes indicate the kind of simulant. It takes a lot of experience to learn to separate the genuine from the imitation, even with the “tests”. If you are unsure of your stone, TAKE IT TO YOUR LOCAL JEWELER!!. For a small fee and a lot of times free of charge, you can be sure. In the meantime, look at a lot of stones, compare known gems against known fakes, gemology is fun to learn an will keep you busy for a long, long time!
December 3rd, 2010 at 2:35 am
can and do diamonds be set in sterling silver sme one told me that diamonds being set in sterling silver just doesnt happen.
December 3rd, 2010 at 2:36 am
some one told me that diamonds dont and cant be set in sterling silver is that true?
January 22nd, 2011 at 8:40 pm
Here’s a sure fire easy way to tell if your diamond is real. Put your diamond under a black light. The diamond will have a faint glow. There will be no brilliant reflections. More importantly, the inclusions will turn solid black. With a 4x magnifying glass from walmart, you will be able to count the inclusions. You have a real diamond if you see those small black spots. If not, you have a CZ or a lab grown stone.
January 26th, 2011 at 4:41 pm
Diamonds are forever! tee- hee
April 6th, 2011 at 8:12 am
Another great inclusion, I really couldn’t have reported it far better by myself.
June 2nd, 2011 at 4:52 pm
i have my husbands grandmother’s wedding ring and went to get it appraised. at first they thought it was a minor’s cut diamond but then said it wasn’t.. what is this stone…
June 16th, 2011 at 3:08 am
use a laser beam if the star specs of tiny lights are not crystal clear its fake if its very clear pin points of light its real
June 16th, 2011 at 3:11 am
wish i knew his before buying fake jewlry for 87 dollars for a 1$ ring this time no one will ever be able to scam me or anyone of you. look at a real ring and most likely you wont see a whole under neath or fake diomands have wholes sin the bottom ring beneath it
June 20th, 2011 at 3:06 pm
Wow, Ronald. Question, I found a stone in a parking lot the other day that I believe is either a CZ or a Diamond. It is approx the size of a princess cut .5ct diamond. It does have a couple of chips in one of the corners (perhaps from laying in a parking lot for who knows how long). It is very colorless. I cannot read through it, however. When held up to a blacklight beside another diamond, the known diamond had a blue glowing hue. The stond did not glow. It looks very similar to a diamond, so I’m not sure. It does cut glass, but I haven’t tried to scrape it on the sidewalk or with a nailfile (gosh, people, what are you thinking>?) Is there any other way not addressed here that a jeweler would use to identify a real from a fake? I don’t really want to take it in and be made a fool of if it is not real.
July 1st, 2011 at 5:05 pm
@ jamie- If you go to a jeweler to test the ring, you won’t be made a fool of if it’s not real.
They deal with that all the time. I ordered a diamond ring from ebay and the day it came in I ran to my local jeweler to be sure I got what I paid for. (It is real) You found that ring, it’s not like you got scammed into buying it., sweetie. I just tried the black light test with my known real diamond and one I was unsure of and the real one didn’t glow a lot, but I know it’s real. The stone I was unsure of was glowing pink, I think we can say that’s a fake. Anyway, don’t be shy and go see the jeweler, they can help you tremendously. 
July 4th, 2011 at 8:39 am
Dear Sir/Madam,
I have recently bought a dimond ring with GIA certificate from a Jewllery Shop. Is it still possible that the Diamond is fake? How can know the GIA certificate is for the diamond I bought?
Your opinion will be appreciated.
Suzy
August 4th, 2011 at 6:15 am
i have a 14 karot sapphire diamond surounded ringand i tried the fog test and it worked my sapphire and diamonds all 26 of them are real thx alot
kervell
August 6th, 2011 at 9:54 pm
I have been going through my mom’s estate and when I run across something I am not sure about, I just go to the jeweler I have used for several years. She has a pen device that she just touched to the stone and voila, I have my answer. She’s also been helping me confirm gold and silver pieces.
August 21st, 2011 at 9:06 pm
I just happened on this site last nite. I wanted to share a better way of testing than the newspaper test. You get one of the mechanical pencils, either .05 or.07 lead will do and a white piece of paper. draw a solid straight line on the paper. Take your diamond and lay it table side down on the line making sure the line runs dead center to the diamond. Now if you look straight down on the diamond. If it is a real diamond you will not see the line. If its fake you’ll either see the line or you’ll see the color of the lead. I learned this and it has been 100% foolproof as long as Ive done it. My jeweler told me a few years back to be wary of purchasing diamonds using this method because now there are some CZ’s that can pass this test but so far I haven’t found one. Im mot sure how white saphires would react to this test but have a friend who has one and am going there tomorrow to find out! Curiosity ya know.
August 25th, 2011 at 6:23 am
This was incredibly helpful, I have to say many thanks to the writer as it has helped me find out if my girlfriends ring is actually a diamond. (It was) Many thanks for wrting this as it will come in helpful for me many times, and I am sure it will be helpful to a great deal more people than me.
September 7th, 2011 at 7:56 pm
Hello, I have 400 grams of raw diamonds (small and big ones) (if you call this way), a couple of workers of mine found them, is there anyone knwos who will buy them?
“they are real diamonds”
September 21st, 2011 at 1:41 pm
found a box of deceased grans jewerly not sure what it is worth
September 22nd, 2011 at 5:44 am
Recently i let my husband take my full diamond and garnet eternity ring to see if it could be enlarged, he was told that the ring had to be sent away a we could collect it in two weeks i did not go ahead with having the ring enlarged with the jeweler as they wanted to cut it an add some gold but it would ruin the ring, I went to another jewelers and explained to them what i wanted done an on testing my ring i was told that the diamonds had been removed an fake stones placed how can i get the first jeweler to replace my diamonds without sueing them?
October 19th, 2011 at 7:49 am
nice article…looking forward for some more from your side..
November 18th, 2011 at 10:23 pm
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November 24th, 2011 at 10:36 am
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November 27th, 2011 at 10:14 am
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November 28th, 2011 at 10:44 pm
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December 1st, 2011 at 2:39 am
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December 23rd, 2011 at 9:19 pm
Found a loose diamond on the way home from work (yay NYC). I give it a 90% chance that it is a CZ but I’ll have it tested and report back tomorrow.
December 24th, 2011 at 2:27 pm
If it’s really that difficult to tell what is a real diamond and what isn’t, what is the point of buying a real diamond? I don’t care to invest via jewelry. I just want something to look nice. So why not just buy the cheap stuff if no one can tell what’s on my ear or hand?
December 25th, 2011 at 2:01 pm
Amazing post, wish I could come up with news like that for my blog, haha.
December 27th, 2011 at 2:40 am
@Jennifer
the point of buying or finding a REAL diamond is the value. Money.
January 4th, 2012 at 8:07 am
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January 6th, 2012 at 8:42 am
I noticed on this site that a lot of people are having trouble identifying a real diamond from a fake one. I purchased a diamond tester on ebay and used real known diamonds against known fake diamonds and glass. Because glass is silicon based and diamonds are carbon based, the diamonds will conduct a small amound of electricity.. this causes my diamond tester to light up and indicate CZ and glass. My tester cost about $20.00 and you can buy a more expensive diamond & gemstone tester to help identify gems etc. I hope this helps.
January 9th, 2012 at 9:11 am
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January 9th, 2012 at 9:51 pm
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January 10th, 2012 at 2:50 am
Just wondered what does a purple hue(glow) mean on a gem (diamond or CZ)? And a dark yellow hue (glow)both under a black light??
January 11th, 2012 at 9:01 am
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January 11th, 2012 at 10:28 pm
Thanks for such an informative site. I purchased a pair of earings for $3 from a garage sale which could have been either diamond or CZ’s. They are set in 9ct gold. I tried the fog test on them and compared the results with my diamond engagement ring. I am now quite satisfied that the earings are either CZ’s or white saphire. It would have been nice if they were diamonds, but I still got a bargain with my CZ’s, they have a beautiful sparkle and a nice solid setting. Thanks for saving me time with your web page and all those people that have supplied useful information. Cheers