Your Guide on How to Identify a Raw Diamond

Due to their incredible durability and sparkling beauty, diamonds are one of the most sought-after gemstones in the world. While it’s easy to recognize a cut diamond, however, not many people would be able to tell whether an uncut or raw diamond is the real thing or not.

Uncut rough diamonds look very similar to water-worn quartz pebbles. However, there are other rocks that can be mistaken for raw diamonds by people who do not know how to spot the precious material. Luckily for people who want to learn how to identify a raw diamond, there are various ways to identify a raw diamond with a high degree of certainty.

This brief guide will go over the most effective ones, classified into two categories. The first category encompasses various observational methods that take into account the physical properties and geological location of the potential raw diamonds. The second category encompasses different tests that can help determine the authenticity of raw diamonds.

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Physical and Geologic Properties of Raw Diamonds

raw diamond pieces


Before learning how to identify a raw diamond, it’s important to realize that diamonds are created in relation to specific geologic conditions. With that knowledge, it will be easier to identify an authentic raw diamond by learning where it came from.

Most diamonds are formed near kimberlite pipes, ultrabasic igneous rocks that contain at least 35 percent olivine and do not contain any quartz or feldspar. Typically, the kimberlite pipes that contribute to the creation of diamonds are the ones located in ancient cratons. Craton is a word that is used to describe the oldest and most geologically stable portions of a continent.

Not all diamonds occur in relation to kimberlite pipes. However, a great majority of them do. It’s not rare to find a raw diamond deposit that is far away from any kimberlite sources. However, in most cases, those deposits can be clearly backtracked to kimberlite pipes that eroded and deteriorated hundreds or even thousands of years in the past.

At this point, it’s important to mention that there are exceptions to the kimberlite pipe rule. Diamonds can also be formed when deep crust tectonic motion creates the pressure and heat that are needed to transform carbon into diamonds. Often, that process is associated with the existence of lamprophyre dikes. However, there are other formations that can lead to the creation of diamonds. These include lamproite rocks, high-pressure metamorphic rocks and even meteorites.


Without a doubt, crystallinity is one of the most important things that should be taken into account by those who want to know how to identify a raw diamond. The reason for this is that diamonds are a part of the isometric crystal system. Typically, diamonds are formed as octahedral crystals. This is very important to know because quartz, the gemstone that is most often confused with raw diamonds, are normally formed as hexagonal crystals. By taking into account this essential difference, it is possible to determine whether a stone is a raw diamond or a quartz.

Specific Gravity

Those who want to know how to identify a raw diamond would be remiss not to learn about specific gravity. Simply put, specific gravity is the ratio that exists between the density of a gemstone and a reference liquid. Typically, this liquid is pure, distilled water, a liquid that has a density of 1 g/mL.

Diamonds have a specific gravity of 3,1 to 3,5. In comparison, quartz has a specific gravity of 2,6 to 2,7. By learning what the specific gravity of a gemstone is, it is possible to know with certainty whether it is a raw diamond. This property of diamonds also serves as a way to separate them from other gemstones using shaker tables or similarly-purposed tools.

Raw Diamond Tests

raw diamond ring on a model

Hardness Test

The reason why hardness is an important factor for those who want to learn how to identify a raw diamond is quite simple. Diamonds are the hardest mineral that occurs naturally. Talc is the softest mineral known to man and, as such, is ranked number one in the hardness scale. On the other end of the spectrum, diamonds are ranked at 10. In order to produce this test, a hardness test can be purchased.

Thermal Conductivity Test

Another method that is very often used to identify raw diamonds is the thermal conductivity test. This test is based on the fact that diamonds disperse heat much more effectively than other gemstones. Using a flat, clean surface, it is possible to determine how quickly the heat is dispersed by the potential raw diamond.

Microscope Test

Often, people who want to know how to identify a raw diamond are glad to find out it is possible to do this just by looking at the stone. However, it is also necessary to use a 10x power jeweler’s loupe or, even better, a microscope. There are two main things to look for when trying to identify a diamond. The first is its appearance; under the microscope, diamonds look as if they had been coated with a thin film of Vaseline. The second thing to look for is certain markings such as indented triangles, parallelograms or rotated squares.

Scratch Test

Luckily for those who want to know how to identify a raw diamond on the spot, there is a final test method that is reliable and effective. Typically, it is done by rubbing the suspected diamond on a synthetic ruby or sapphire (corundum) plate. Because they are just below diamonds on the hardness scale, rubies and sapphires are the perfect material to test a possible diamond with. Simply put, there is no other material that would scratch a plate of the kind. Logically, if the stone scratches the plate, it is an authentic diamond.

Wrapping Up

Not everything that shines is gold, and not everything that sparkles is a diamond. Luckily, this quick guide will give you a better grasp of what to look for when trying to identify a raw diamond.

Do you know any other methods for doing this? Let us know!

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