How can You Tell if a Diamond is Real?

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  • Originally Written By: S. Mithra
  • Revised By: Mary McMahon
  • Edited By: L. S. Wynn
  • Last Modified Date: 16 December 2018
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If you are browsing gems or jewelry for sale and want to quickly determine whether a clear stone is a diamond, there are a few easy tests you can apply without any special equipment. The popular test of scratching the stone across glass or metal isn't very reliable, and might just give you a damaged gem; instead, looking at the way the stone reflects light or if it fogs up when breathed on can give you a better indication of whether or not it's a real diamond. These tests rule out recognizable imposters because they rely on the way a real diamond refracts light, conducts heat, and looks up-close. The only people who can authenticate a stone are certified gemologists specializing in jewelry, however; their services are available for a fee.

The Print Test

If the gem in question is loose and unmounted, try placing it over printing. Diamonds refract so much light that they will not work as magnifying glasses and you would see no lines, circles, or letters through them. Other clear stones like glass or crystal will reveal the print clearly. Be careful: Depending on how a diamond is cut, the print test is not completely reliable.


The Light Test

A similar test uses a small light, such as one that can be carried on a key ring. If you shine the light through the stone and see only a bright halo around the rim, it is more likely to be a true diamond. Looking at the shadows cast by a stone can also help determine what kind of gem it is, as real diamonds typically cast grayish shadows, not rainbows.

The Breath Test

Diamonds are also very good at conducting heat. Breathe on the surface of the stone and immediately check to see if it has fogged up. Quartz, glass, and cubic zirconium will stay hazy for a moment before the condensation dissipates, but you shouldn't be able to see any moisture on a real diamond. One rock, called moissanite, will also pass this test, so it is not completely reliable. If you aren't sure about the stone, you may need to get a complete thermal conductivity evaluation performed by a jeweler.

Look Up Close

Looking closely at the specks, ridges, and facets can give you a clue into the identity of your gem. Diamonds do have inclusions, which are tiny bits of other minerals that were crushed into the stone while it formed, so impurities don't mean a gem isn't real. If the facets have worn or rounded edges, or if the stone looks rippled, bubbly, or pitted, it is probably glass. Gems that are perfectly clear, with absolutely no inclusions, may be quartz.

Tests that Require Tools

If you have some additional tools at your disposal, there are more advanced tests you can use to assess a stone offered for sale. An instrument known as a diamond/moissanite tester evaluates the thermal and electrical conductivity of a stone to determine if it is genuine or a simulant material. Using a scale, you can also compare the weight of a stone to a real diamond for reference; if the weights are different, this is an indicator that the stone is fake. Viewing a diamond under ultraviolet light usually reveals a flash of blue, although very high quality stones don't always do this, so the absence of this color change doesn't necessarily mean a stone is fake.

Certificate of Authenticity

A seller may also have a certificate of authenticity along with the stone. Review it carefully to determine who issued it, and look up the standards for the sponsoring organization. If you have questions or concerns about the certificate, consider bringing it to a reputable jeweler for examination; jewelers may offer a quick consultation at no charge.

Examine the Setting

Stones commonly used in place of natural diamonds include cubic zirconia, moissanite, glass, quartz, and synthetic gems grown in lab environments. These are often placed in settings of low quality because they are worth less. Some warning signs that a piece of diamond jewelry may be fake can include metal that is flaking, pitting, or eroding, along with the absence of a stamp inside the setting to disclose the metal type.

Common Sense Tips for Diamond Buying

Some common sense measures can help prevent you from being pressured to purchase a gem that turns out to be something other than a diamond. It shouldn't be ridiculously inexpensive, or you'll get what you pay for. Real diamonds also will usually be mounted in an "open back" setting, which means that you can see around the rear of the gem and the back surface isn't coated with any silvery substance. True diamonds can also fracture or crumble because of inclusions, so hitting or crushing them as a test is not advised.

If a stone looks like the real deal, assess it for the four C's: Carat, Color, Clarity, and Cut. These can determine the value of a diamond by considering its size, visual appearance, and faceting. Blemishes inside the stone can degrade its appearance and stability, while a poorly-cut stone may fail to shine to its best advantage. Buyers should be aware that while these stones are famously depicted as white, they can be pink, yellow, blue, and other colors; these "fancy diamonds" can sometimes be more expensive if the color is unusually rich or rare.

Diamond Sources

Even many gemologists cannot distinguish "real" diamonds from cultured stones. Cultured diamonds have been artificially produced in a laboratory, not mined, yet they are chemically identical to naturally-formed rocks. Some companies are developing new kinds of identification methods for those who would like to purchase a mined diamond as well as buyers who prefer cultured stones.

Advanced certification is also available for consumers with ethical concerns about diamond sourcing. These programs attempt to track stones from source to end consumer to assure buyers that they are not purchasing so-called "conflict diamonds" that fund insurgencies. Reliability of these certificates is variable and, as with proofs of authenticity, it is a good idea to look up the organization that backs the program to learn more about it.


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Discuss this Article

Post 99

You definitely want to take extra precautions when purchasing a diamond from an unauthorized seller. These are all very good methods of determining if a diamond is authentic or not. Knowing the 4 C’s is a great system to use when examining your diamond: Cut, Clarity, Color and Carat. Or take it to a certified jeweler.

Post 98

Which glasses are used to detect raw diamonds at night?

Post 94

My engagement ring was bought in 1982 at a wholesale jewelers and they gave us an appraisal stating it was .53 carat color F Clarity VS1. We paid around $1500.00 and the appraisal states it is worth $3200.00. I just had it appraised again at a different location as I have moved 1.5 hours away. This appraisal came back as .62 carat color H clarity SL1. Is there anything I can do about this? What should my next step be?

Post 93

I have a wedding set that is marked 14KP and is white gold. I believe it's a 2 carat stone, but would they put cubic in plumb gold?

Post 92

I found a diamond in Washington D.C., but i don't know if it's a real diamond.

Post 91

Anybody tried the app Ratemydiamond? They claim to tell you the value of your diamond!!

Post 90

My friend bought a 2.5 karat tw 14k ring (that's what the tag says) but it's also says its a lynx cable view demo. It's a waterfall cluster ring. And we are trying to see if the diamond are real.

Do jewelry stores put real diamonds in their demo jewelry? How can we check to see if the diamonds are real? There are 19 small diamonds all addinf to be 2.5 karat tw. On the tag, they spelled carat with a k instead of a c.

Post 89

I found a crystal in third grade. I took it out of my box and I found out it is worth tons of money. What should I do?

Post 88

I am dheeraj. I found a stone that is white like a diamond, but not as hard, and this stone glows in the dark like radium. How can I know what this is?

Post 86

I have a diamond pendant for a necklace. It's a light purple and an open back. I can barely read through it but I can and it is plated with 18kgp xp. Is it possible it's real?

Post 85

I purchased a so-called 0.02 ct diamond, however a diamond tester does not show it as a diamond. If the diamond is this small, will it still show up on a diamond tester?

Post 81

My grandmother buys me a lot of jewelry. i have a pair of blue sapphire and diamond earrings and jade and diamond rings and such. how much would it cost me to get insurance on all my jewelry?

Post 79

I was wondering how one can tell the difference between a real diamond and a fake? What are the characteristics one should notice in a real diamond compared to a fake diamond or CZ? For example, with one of my rings, the diamond glows brightly under a black light. When I compared my ring's "glowing" to another girl's ring, her diamond barely glowed. What is the explanation for this and is my diamond real?

Post 77

Unreal. If you buy a diamond it should come with certification, EGL, GIA etc. If there's no certificate; don't buy it, or be upset if it turns out to be fake. It's your responsibility to ask for the certificate. It's really that simple.

If you have a stone that you found (I notice no one is trying to find the original owner, nice ethics you have) or were given, contact GIA and find an authorized gemologist in your area, they won't rip you off, GIA is the most respected diamond grading organization in the world.

Post 76

I need to talk to a geologist ASAP. I have what appears to be a large diamond. At least 20K, maybe 40 and passing all tests. This appears to be a little bit larger than the hope diamond.

Post 75

Sorry, forgot to add to tests: if you have UV light, put diamond under and it should show off blue.

Correction to coloring, if stone shows color, could just be low quality stone. But mine shows rainbows.

Always do a collection of tests. Quality of diamond can give different results. Moisture and UV seem to be most important tests to pass though.

My engagement ring is from Diamond NExus labs. I found the packaging the first day. I'm no dummy. Anyway, the stone, which many say is CZ, reflects minimal light, cuts glass, lasts just a second over the moisture test, and doesn't allow you to read writing through it. So, as you can see, do a few tests. And

don't trust jewelers.

A friend of mine has a really high quality diamond. Literally, straight from the miner to his Dad's hands. His Dad also had high education in stones. Anyway, went to jeweler to get it set for his GF, and jeweler was trying to convince him it was fake. He didn't even ask for an opinion on the stone quality. And never leave your stone alone with someone. Ask them to test it in front of you. So beware!

Post 74

There are a few tests you can do. First is just exhaling on the stone, moisture shouldn't stay on for more than 2-4 seconds. But if there is anything on the stone (oils) it can give a false result. Second, see if you can read something through the stone. You should not be able to read anything. Third, cut glass, but some CZ can cut glass too and you can mess up the diamond. Four, diamonds don't reflect a lot of light. If you put the stone up to some light, you should not see a rainbow of colors. Diamonds mainly reflect grays. How do I know this? I found out my engagement ring is fake! Not angry but

more upset at why my fiance would do this.

The ring I have is really pretty and it passes all tests but the color test. It is a high quality gemstone but still. I know it was a save money for better start in marriage thing, but still, would rather have been included.

Post 73

what will happen if a diamond is burned in 1400 degree fahrenheit?

Post 72

i have diamond i had tested by a diamond tester. it said that is diamond hard 10 but i went to an idl lab and they say that is synthetic ruby ???

note i had it tested by many diamond testers and it give me the same result, that it is a diamond. what can i do?

Post 71

to post number 33: that makes your son and you a thief. If he found it in your brother's car that makes it your brother's not yours. That's like saying my son found this in my brother's house. I'm sure they are looking for it so just give it back!!

Post 70

@68: No they cannot.

@24 Yeah, but it didn't work on my known real stones.

@27: If it fogs, it's a fake.

Post 69

Can a diamond be purple and clear looking?

Post 68

real diamonds cannot be scratched on sand paper.

Post 67

saying a diamond is fake if you can read something through it is false. It depends on the way it is cut that allows you to see through it. Case in point: the old miner's cut, or cushion cut has fewer points or facets, and thus allows you to see through it. Don't be deceived by an old crook's test to get your stones. Beware!

Post 64

I have a stone of max 20 grams. i think there is diamond in that stone. how can i check?

Tell me the machine so that i can check the said stone.

Post 63

@29, possibly citrine and smokey quartz.

Post 62

Diamonds are very hard, but they can be brittle; much more so than glass or crystal, so breaking a stone doesn't mean that it was not really a diamond.

Post 61

I bought three fairly large diamonds in Sierra Leone in 2001. They scratched glass but were quite dull in appearance. A friend of mine insisted they weren't real and demonstrated this by biting one in half. So I threw them away.

Post 57

This guy at my school claims that he has real diamonds and I don't believe him. How can I check if they are real without bringing him to a jeweller. Kindly waiting your reply!

Post 56

please i found a stone and i think it's diamond. how can i know if it's a diamond?

Post 55

I found a diamond ring, It is gold (real gold) and looks very old.I tried smashing the diamond (if it smashes, it's fake) because diamonds are very strong and it looks real!

Post 53

I found a diamond in the road near my house and took a piece of glass and used a press against it and i chipped a piece of tempered glass the kind they use on aircraft. i think i just became 1,000 dollars richer just by walking.

Post 52

A person at a pawn shop once told me that to tell if it was real, try to stick it to glass. If it sticks, it's real. I found a diamond at a baseball park and i tried to stick it under my glass table and it stuck. I also was able to stick it to my glass sliding door.

Post 51

RE answer number 38: I don't think it is true that diamonds have no real value, and that it is just in the eye of the beholder, type of thing. That may be true, if all you mean is an ornamental gem, but diamonds, and even diamond dust, are used in an industrial way, for machines, saw blades, etc., and so they have a certain market value due to those other uses also.

Post 50

In 2009, I bought a ring at an auction, and then took it to a local jeweler, who had been in business many years. He did not charge me anything to tell me whether it was real or not.

I had him do the work so I could have the official paperwork (GIA), which included cleaning it, photographing it, and so on. He did a very nice job. It cost me $60 for all that, but I was glad to have the official paperwork, which includes all the criteria, the cut, color, weight (carats) and clarity.

All of those issues determine the value of a diamond, not just the fact that it is a diamond of a certain size. The replacement value, stated on the certificate, is over $2400.00.

So if you want to know whether it's a diamond, ask a real jeweler.

Post 49

i lit up the diamond that i found the other day with a lighter. it got very, very hot and remained hot for quite a while. I have another fake diamond, which does not get as hot as the other one, so what does this mean? do diamonds get very hot if kept in fire?

Post 48

so long as your stone looks pretty and you like it, why worry if it's real or not? beauty is in the eye of the beholder. my soon to be husband bought me a beautiful trilogy engagement ring, our past, present and future. isn't that what really counts?

Post 47

I just bought a diamond tester because I wanted to test a diamond that I purchased. If you want to check a diamond I suggest you buy a diamond tester. Then you will not get taken for a ride.

Post 46

'i found'/'he found'/'she found' in a 'draw'(sic)/ car /playground. etc. it's amazing how people are everywhere carelessly chucking their jewelry around where others may happen to find it

Post 44

how can i tell if it is a real diamond when you find it on a playground.

Post 43

Can a store, say in a mall, sell me a fake diamond? because i bought a heart shaped 10k gold ring. some person up there said my kind of ring is fake. it cost $230 and it's small, passed the breath test. and i got lifetime warranty and cleaning with them? how do i know?

Post 42

I found the best way to see if a diamond is real is to use a diamond tester. There are many manufactures that make diamond testers.

I found a site that offers them wholesale!

Post 41

goodness me, all this hoohaa about real and fakes. if you're going to spend money on a diamond, or if you're worried about jewelers lying about its authenticity. surely it's worth buying a diamond tester.

i came on this site for answers and the only one i got was to invest in a tester. All the above tests are irrelevant if your diamonds have been set in jewelery.

Post 38

@William. [ "Diamonds have no real value at all, the value is in the eye of the buyer. Try buying one and then sell back to the jeweler."]

Of course you won't get the same value back. The jeweler has to turn a profit, right?

Post 37

i had found a piece of white stone weight 2.00 Kilogram (approx.) and 15cm X 10 cm. please give me some suggestions. i am suspicious about this stone. please send your feedback.

Post 36

Is there such a thing as a white diamond?

Post 35

this may be a dumb question but when doing the line test, do you look through the flat top or the pointed bottom or doesn't it make any difference?

Post 34

Could someone advise me if a jeweler might be able to tell the difference between a raw diamond and a raw quartz crystal? My son found this rock, years ago, and we have always wondered what it really is. It does cut glass, if that matters.

Post 33

OK my boy found a diamond in my brother's car while he was looking for some change to go skating. It's about 1k marq. it was on some cheap/tarnished chain but the setting on the diamond was real nice so I have been running all these testd on it and it's passing every one of them. I might have gotten lucky for once in my life. the setting is what caught my eye on this. why does a cz have such a good setting on it with a cheap chain? something just wasn't right. well I think it's real, I will take it to a jeweler though.

Post 32

I just bought a pair of 1.00 Cttw online for $99 in 14kt gold online. I can't believe the price: $99! I even got them tested and they are 100 percent real blue diamonds! Is this a good price for these and what do they usually go for?

Post 31

I found what looks like a diamond. i did the glass test and it cut the glass. i did the line test and the black felt test. it looks like about 1 carat size. i had it for about a month after putting an ad in the paper. no one claimed it. how can i have a jeweler look at it without swapping it if it is real? i'm not allowed to go in the jewelers office. I've known them for years.

Post 30

hey i brought a diamond ring. well i was told it was a diamond ring and i was just wondering if you have a hot shower and get out will it be fogged up or will it be stil be shiny and clear

Post 29

I found a pair of clip on earrings in the back of a draw in a new house we moved into. They have a big yellow something in the center. it would be nice if it was a yellow diamond. the yellow stone in the center is surrounded by 16 little brown stones of some kind. Since the stones are set into the earrings, it's a bit hard to do quick light tests etc. Anyone got any other ideas?

Post 28

Take it to a jewelery store and ask. They have those testers and they test right in front of you. It's that simple. If you try any of the "do it yourself" tests...are you really satisfied??...No So take it to a jeweler. Discussion over!!!

Post 27

What's that one trick of putting it in the freezer again?

Post 26

I found a round shape 18k gold medallion w/ a broken chain 4cms long, weighing 90 grams. On it's side are 8 pcs.-white stone I presumed to be diamonds 2mm diameter. When I tested it on the window pane, it cuts and divides the glass smoothly like a glass cutter. Is this a true diamond?

Post 24

anybody ever do this test. put stone on a mirror turn mirror side-ways if stone stays it's a diamond if not then it's a fake

Post 23

The best thing to do is buy a reliable diamond tester. One that can test moissanite, CZ's and real diamonds. I found one that works great from a tool supplier. The company is called StarStruckLLC and their delivery was quick. I suggest you buy one from them and sleep well at night.

Post 22

i just bought my girlfriend a diamond ring and i asked a jeweler to look at i and it turnded out to be more exspesive than what i paid for $250 and it was worth $1000

Post 21

re. heart shaped stone - if it is set in 10ct gold it is unlikely to be genuine as heart shaped stones are probably the most difficult to cut and produce.

re. diamond bought from india - I think you've been had, trust a reputable jeweller in canada. if in doubt, ask them to thermal test the stone in front of you.

Post 20

i have a heart shaped what looks to be diamond ring it has a 10k stamp and a AFJC stamp

Post 18

How do you determine if you have a rough diamond? It's weight is 32 grams I tumbled it for two day in carborundum #90 and the weight didn't change. It scratches metal and glass.

Post 17

Diamonds have no real value at all, the value is in the eye of the buyer. Try buying one and then sell back to the jeweller.

Post 16

i recently purchased a diamond from india and i went to a few stores in canada to check if its real and they told me it's fake. how do i tell if the canadian jewellers are correct?

Post 15

Have a friend who works at a hospital or is an X-ray tech to x-ray it.

Post 14

It is very easy to determine a real diamond from a fake!

All that you need to do is buy a diamond tester. The tester uses both heat and electricity to separate cz's, moissanite, synthetics all from the real thing.

Post 13

My husband bought my rings through a friend who knows a jeweler. They told him it's real it cost him almost $300. Then when we went with my mom to pick out her ring the jeweler said mine was fake. Who to trust.

Post 12

my boyfriend got me an engagement ring and i don't care if it is real or not so i'm not going to ask him but how can i tell if it is real?

Post 11

hello guys you want to know if it's real or not draw a line on a paper and move the stone above the line. if you can see the line that means it's fake if you can't see the line that means it's a real diamond.

or you can buy a tester and check it but i always use this trick

diamond you can't see through it.

Post 9

I am worried - my diamond was purchased from ShaneCo (a reputable store) and i did the breath test and it does fog up for a moment. did they sell me a fake diamond for 8g???!!! It did not come with any papers "only some of their diamonds come with certificates, etc".

Post 8

I went to Las Vegas this weekend and found what looks like a diamond, on the floor. It looks real, and is extraordinary, but I can't be sure. Is there a simple way that I can know if this is a diamond, without a doubt? Please respond.

Moderator's reply: my suggestion would be to take the stone to a REPUTABLE jeweler, and ask them if they can examine it in front of you. if it is real, then you should probably call the local police department to report it as found. if it goes unclaimed, you may be able to keep it!

Post 7

my advice is to buy your diamonds from a very reputable store that will certify it for you. although you may pay a bit extra for the certification, you should feel confident that it is real. my crazy dad who is always trying to get a deal wanted to buy my mom a new diamond and got ripped off by some random diamond dealer. it turned out to be cz!

Post 6

I heard if you put your diamond on black it can let you know if it is real just don't remember if it is clear black its real or if you can't see clear? Does anyone know? Please Respond.

Post 5

I don't want to take my diamond to a jeweler because if it is real and they say its not and I sell it to them for something cheap it could be real and i could be ripped OFF!

Post 4

Wasn't there also some test about putting the stones in the freezer?

Because the internal temp of diamond being so low, something, and I can't remember what was supposed to help distinguish between diamond and an imitation.

Post 3

every time i go on the internet to check if there are any solutions to my diamond problems, they are always talking about when you BUY the diamond. Well, i FOUND my diamond in a bush??? So how does your info help me there?

Post 2

How can you tell if your diamond is fake or real without buying anything to test it?

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