7 Ways to Spot Fake Diamonds

Have you ever been suspicious that a loose diamond you were sold wasn’t real, or wondered whether your diamond jewelry was genuine? With such a high-value purchase, it’s almost impossible not to be a little apprehensive about the authenticity of your diamond. Many people consider at some point that the diamond they purchased is not real, especially if it does not come with a GIA certificate.

Looking to buy a real GIA certified diamond? Start here.

There are two great ways to help assuage worry and uncertainty about the genuineness of a diamond. First would be to completely stay away from diamonds that are not certified. My first piece of advice is to purchase from trusted vendors, like Ritani, who sell only high quality, GIA certified loose diamonds.

If buying a certified loose diamond is not the route you take, though, my advice is to test the diamond as much as you can, both at home and at a trusted local jeweler. There are quite a few ways to easily test whether a loose stone is a real diamond or a fake. Fake engagement rings, such as diamonique engagement rings, can be detected through these simple tests.

Should you try the scratch test?

Once thought to be the easiest way to spot fake diamonds, the “scratch test” involves simply scratching the loose stone against a mirror to test its hardness.

When you think about this test in terms of the Mohs scale, however, this test proves inaccurate. Invented in 1812, the Mohs scale measures mineral hardness. Glass is rated a 5.5, and diamonds are a 10. So, genuine diamonds will scratch a mirror. On the other hand, so will quartz (7), moissanite, and cubic zirconia (8). Cubic zirconia engagement rings are almost as hard to scratch as their diamond counterparts.

Most well-made synthetic diamonds will seem authentic if you only use the scratch test. Here are some other tests with more reliable results.

1. The Magnification Test


A loupe, which is a 10x jeweler’s magnifying glass, can tell you a lot about whether a diamond is real or fake. If you have a powerful magnifying glass and a genuine diamond on hand, you can easily perform this test at home. If you don’t have a real diamond to compare your loose stone to, though, I suggest heading to your local jeweler.

Fake diamonds, such as cubic zirconia or moissanite engagement rings, will look a little too perfect when examined under a loupe. All diamonds have their inclusions, and even Ideal cut diamonds will have some internal quirks. On the other hand, most fake diamonds are created to look totally flawless, and will look quite different under a loupe than a natural diamond.

2. The Fog Test

This test does not refer to taking your diamond out on a foggy day, but rather creating a “fog” around the stone by blowing on it. A real diamond does not retain heat well, so even if you blow on it with hot air, it will not get foggy.

On the other hand, a moissanite engagement ring will get a fog that then fades away, just like a mirror or the screen of your cell phone.

3. The UV Light Test

Diamond fluorescence chart. Photo credit: Adiamor.

This test is not quite as reliable as some of the others in this post, but if you take your loose stone to a professional jeweler you can get some more definitive answers.

As I outlined in my Diamond Fluorescence FAQ, many diamonds will glow blue under UV light. If you have a strong UV light on hand, you might be able to try this test at home, but I recommend going to your local jeweler. Jewelry stores always have high-powered UV lights to test and demonstrate diamond fluorescence.

4. The Newspaper Test

A real diamond should refract light so intensely that you cannot see through it. So, if you have a loose stone and are unsure whether it is a diamond or cubic zirconia, try the newspaper test to check the transparency of your diamond.

Grab a piece of newspaper or a page of a magazine and place the loose diamond on top of it. If the stone is a diamond with a decent cut grade, it should sparkle enough that you cannot see through it to read the words on the page. With CZ engagement rings, you should be able to see right through.

diamond 2

5. The Lighter or Candle Test

A word of caution on this test – only perform it if you don’t care about destroying the loose stone if it’s fake.

Because diamonds are such an incredibly strong material, this test will not break them. However, many fake diamonds – including those made of glass, cubic zirconia, or quartz – will break or shatter during this test.

First, heat up the loose stone over a lighter or candle flame for about 30 seconds. Then, immediately drop the stone into a glass of cold water. A real loose diamond will not react at all, despite these extreme temperature changes. A fake diamond will likely crack or shatter from the inside.

6. The Float Test

Because loose diamonds are so dense, they should sink to the bottom when dropped in a glass of water. Many diamond fakes – glass and quartz included – will float or not sink as quickly because they are less dense.

This test is not foolproof; I would recommend trying more than one test rather than solely this one. Heavy cubic zirconia and moissanite have the ability to dupe this test.

7. The Conductivity Test


This is another test that you’ll have to visit your local jeweler for. Something that not too many people know about diamonds is that they conduct electricity.

Testing a loose stone for conductivity is especially helpful if you aren’t sure whether your stone is a diamond or moissanite. Moissanite (if it is made well) can be extremely difficult to tell apart from a genuine diamond. One relatively simple way to tell the difference is that moissanite will not conduct electricity with as much strength as a diamond. With the rise of moissanite in today’s diamond market, the majority of jewelers will have an electricity testing tool on hand to determine the real from the lab-created.

If you have a loose stone or piece of diamond jewelry and you are unsure about its authenticity, try some of these home tests. Or, bring the stone to any of our free in-store preview jewelers, who are sure to have electricity testing, UV lights, and more tools that can determine the difference between a real diamond and a fake.

Have you ever tested at home or at a jewelry store whether a diamond was real or fake? What were the results? Please share any comparison photos, comments, or additional questions in the comments below!

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