Diamond Articles

How to Spot a Fake Diamond

May 25, 2017 - Diamond Articles

In a world where advancing technology means advancing opportunities to deceive, it is understandable that consumers have been asking the question, “How can I tell if my diamond is fake?” and “how can I spot a fake diamond?”. To know if a diamond is fake, you need to know how to tell if a diamond is real, of course. So here, we hope to show you what to look for, what isn’t quite right, and when further testing might be needed beyond home tests.

A 10x loupe is great tool for checking many of the features listed below. With this, a diamond can also be checked while still in a jewelry mounting. The features to check in order to ascertain whether your diamond is real or fake are detailed below.


How to spot a fake diamond?

    1. Inclusions
    2. External Features
    3. Luster
    4. Optical effects
    5. Does It Float?
    6. Wettability
    7. Thermal Conductivity
    8. Electrical Conductivity
    9. The ‘Read Through’ Test
    10. Consult A Diamond Expert



The first step to spot a fake diamond is inclusions. Inclusions are features that are either wholly enclosed within the gemstone, or extend to the gemstone surface.

What’s normal: crystal (ie. solid, mineral inclusions within the stone, such as garnet, spinel, pyroxene, olivine, or graphite), bearding, bruise, graining, knots (caused from twinning), pin points, clouds, cleavage (a line of weakness in a diamond), chips, cavities, fractures/feathers, or a natural (part of the natural surface left after polishing).

What’s not normal: Certain inclusions just don’t belong in diamond. For example, bubbles are a signature inclusion found in glass. If you see them in a diamond, the gem is not a diamond.



External characteristics are features found on the surface of the diamond, but do not penetrate the stone.

What’s normal: Grain lines, extra facets, abrasion, scratch, burn mark, polishing lines, trigons, and sharp facet edges.

What’s not normal: If the facet edges look a bit dull or worn overall, or not very sharp, you can rest assured that the stone is not a diamond. This is an easy way to compare diamond to softer materials.

It is important to note that diamonds are hard—the hardest natural gemstone. In fact they score a ten on the Mohs scale of hardness. Therefore, when you look at diamond facets with your eye, the edge of every facet will be sharp, due to the hardness of the stone.

Another external feature, an adorable upside down triangle-looking feature called a trigon, occurs naturally on diamond rough. Sometimes it is left on a diamond girdle to maintain carat weight. If you see a trigon, your diamond is certainly natural.



Luster relates to the quality and quantity of light reflecting from the surface of a material. As one becomes accustomed to seeing many diamonds, as well as diamond simulants, luster becomes a factor that helps in quick determination of whether a gem material may be the real deal or not.

What’s normal: Diamonds have an adamantine luster. That means they are bright and reflective, almost mirror-like. The word comes from the Latin word “adamas,” which means “diamond.”

What’s not normal: To compare, here are the lusters you may find in some other materials that look similar to diamond, but aren’t diamond:

  • Sub-adamantine: this is a bright luster, but not quite as bright as adamantine, and can be seen in gemstones such as zircon.
  • Bright Vitreous: this luster is glossier, and can be seen in similar looking stones like white sapphire.
  • Vitreous: this luster looks like glass (and more commonly is glass).



1. Fire

Diamond has fire. Do you recall turning a diamond and seeing all the colors of the rainbow? That is called fire. If you don’t see fire, you are not looking at a diamond. Moissanite has twice the fire of diamond though—so it has to be the right amount of fire.

how to spot a fake diamond

2. Single Refraction

Diamond is a singly refractive material. As light enters, it may be refracted, but it remains a single ray of light no matter the direction. However, synthetic moissanite, and some other diamond simulants have double refraction, so when light enters the stone, it is split into 2 rays.

What does that mean? That means that with a 10x lens, even in set jewelry, it is easy to detect a doubled image of the facet edges or scratches. It is probably the easiest and quickest way to distinguish diamond from moissanite, when suspecting it could be one of the two materials.



No, they do not. In fact, in gem testing an entire system of measurement is used to measure the density of gemstones. This is because the easiest way to compare density is to compare a material to the density of water (Archimedes’ principle). Water is one gram per cubic centimeter (1g/cc). One cubic centimeter of diamond weights 3.5, so its relative density to water is 3.5. This is the basis for the measurement of specific gravity (SG).



Diamonds are not wettable. Like beads of water on a candle, these gems like to resist water. Why does this happen? Unbonded carbon atoms on the surface like to bind to grease-based things (this is why diamonds get dirty: they love greasy things so do be sure to clean them regularly). Therefore, there are few bonds left for water to attract.



Thermal Conductivity is the measure of the ability of a material to transfer heat. Diamonds have a high thermal conductivity, which is why they feel cool to the touch.

For those looking for a fun toy, thermal conductance probes are available for purchase. These can help distinguish diamonds from its simulants even while set in jewelry, with the exception of synthetic moissanite (although moissanite is easy to distinguish from diamonds in other ways).

how to spot a fake diamond



What conducts electricity all day and all night? Certainly not a diamond. This sea of gemstones has no free electrons in their electrical structure boat, so nothing can be charged.

What does that mean for you in learning to spot a fake diamond? Some probes test thermal and electrical conductivity in one (you can also just get an electrical probe).

There are exceptions to diamonds conducting electricity though. If it contains boron, then there are free electrons, but you would be looking at a blue diamond, so you’d anticipate that by the color. Also, synthetic diamonds grown in a metallic flux could have metallic inclusions that could conduct electricity.



This is a fun test for distinguishing a well-cut modern round brilliant from simulants with the same cut:

  1. Draw a straight line on a white piece of paper with a black pen and place a diamond on it, table down, and observe.
  2. Then do the same with a simulant, like cubic zirconia for example.

Result: Because of the total internal reflection of diamond, from above, the black line will not be visible though a diamond. Since most simulants, like cubic zirconia (CZ), have a lower RI, the line remains visible through the gemstone.

There are exceptions to the rule though—strontium titanite, synthetic rutile, and synthetic moissanite do have a higher RI and will show the lines, so just be on the lookout if either of those three are suspect.


10. Consult a diamond expert

Ultimately of course, the best way to know if you have a diamond is to have an expert check to see if you have a diamond. Be sure to have your diamond send for an appraisal at a reputable lab such as the GIA (or be sure that your retailer provides one). Also, only a lab would be able to confirm if a diamond is synthetic. For the purposes of this article, this doesn’t cover information on synthetic diamonds or lab created diamonds, as these have the exact same chemical composition with the difference being that they are lab-grown, as opposed to naturally coming from the earth.

If you are looking to sell loose diamonds, a diamond engagement ring or other diamond jewelry, WP Diamonds is a leading service for selling diamonds online and in-person. Our diamond and jewelry experts can provide you with a valuation, price and check the authenticity of your stone for you. The entire process can take as little as 24 hours, click the button below to get your price quote.

Bio: The CEO/Founder of Pietra PR, Olga González has over ten years of experience working within the field of jewelry communications. A certified gemologist (FGA DGA) and appraiser, she specializes in growing mid to large-sized companies within the jewel...

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