How to Identify a Raw Diamond

The beautifully carved stone you’ve spent a fortune to buy for your engagement didn’t come the way it looks. Though considered extremely precious, diamonds may not be appealing to you at first gaze. These gems are derived from the Earth’s crust in naturally-rough forms. But if you’re familiar with its source and value, you may grow excited when you come across a crystal that looks like one.

But not all gems found in the soil are valuable, and it’s easy to confuse them with diamonds. So, how certain are you that what you’ve found is the real deal? Here, we’ll explore the various ways of identifying raw diamonds by running tests right in your very home. And you’ll also find information regarding raw diamonds, their various types, and how they’re mostly used. But let us first understand how this gemstone comes to being.

What’s a Raw Diamond?

Raw diamonds or rough diamonds are the natural forms of the popularly known fine diamonds. And they form deep in the Earth’s crust and take ages to become what they are. These stones are pushed up from their magma-dominated environments during volcanic eruptions and stay untouched for a long period before humans finally mine them.

According to experts, raw diamonds formed around 90 million to 3 billion years ago inside the Earth. These crystals took form at a depth of 90 to 400 miles below the Earth’s crust, at a temperature of 2,100F. Also, in their parent conditions, the pressure was noted to be 45,000 times greater than what’s recorded at sea level. And in these conditions, carbon atoms were forced to form extremely tight bonds, resulting in what’s recorded today as the hardest gemstone in the Earth’s existence.

Not all raw diamonds survive the volcanic eruptions that expose them to the Earth’s surface, and the reason is that magma can dissolve the crystal due to its extreme heat. But the gems that do are trapped in kimberlite rocks, from which some eventually become free due to erosion. And most of these raw diamonds shatter during the process of being carried downstream by flowing water and accumulate in the alluvial beds of rivers and streams.

Mining of raw diamonds is done in the remnants of the ancient volcanoes that first exposed them to the surface. And from these kimberlite pipes, about 250 tons of ore must be extracted and processed to discover a single one-carat diamond of gem quality. And surprisingly, only 20 to 30% of the raw diamonds discovered in these sites are gem-quality.

Raw diamonds are found in numerous regions worldwide, with their highest producers in Africa. And these countries like Botswana, Angola, DR Congo, South Africa, Zimbabwe, Sierra Leone, and Namibia. But among the list, Botswana and DR Congo make the top five diamond producers worldwide. The former sits at 2nd place in the ranking, topped by Russia, while the latter is ranked number five, sitting one spot below Australia on the table.

Types of Raw Diamond

Raw diamonds generally come in three forms, namely industrial and gem quality. Industrial diamonds are crystals considered best for industrial uses. And among them include the Sergio raw diamonds, which are most popularly used for this purpose, some Cullinan diamonds, and the Tiffany Yellow diamonds. But there’s a variety of industrial diamonds- the crushing-boart, which are considered the poorest quality. These types are ground into dust and used in abrasive industrial applications.

But the gem-quality diamonds are the rarest and most expensive to find. These types adorn jewelry of various kinds and can cost from $1,000 to $70,000 depending on the carat and quality. The Cullinan diamonds produce the highest quality of these types, but you’ll also find options from Tiffany Yellow, Salt and Raw Pepper, and Taylor-Burton diamonds.

How Raw Diamonds are Used

Of course, gem-quality raw diamonds are added to jewelry, and they command incredibly hefty prices on the market. But most raw diamonds are applied to industrial uses. They’re added to the sharp edges of saws and tips of drill bits, where they increase cutting and drilling powder ten folds. And they’re also included in polishing and super abrasion tools, where they improve the wearing capacity of the tools due to their hardness and resistance to pressure.

Identifying a Raw Diamond

Raw diamonds are mostly found in mining areas, but you may still come across one in other places. Still, it helps to know the environmental conditions these crystals may form. Plus, they can be hard to tell from refined or cut diamonds. But you can employ numerous techniques to be certain what you’ve got is the real deal.

But before you jump at these procedures, it’s best to be sure you’re not wasting your time. And your gem is less likely to be a raw diamond if

  • It weighs more than 10 carats (2 grams),
  • It’s larger than 3/8 of an inch (8mm),
  • If you found lots of it in the same area.

But if you didn’t experience any of these, you can proceed to the confirmation steps. For starters, look out for the appearance and condition of the area you found the suspected crystal. And below are the best ways to do this;

  • If the stone is found in kimberlite pipe deposits, there’s a strong chance it’s a diamond. These igneous stones come from molten magma and are mostly found on the soil’s surface. And because their condition of formation is similar to that of diamonds, the latter can be found around them.
  • If you find the gem in water, it may very well be a raw diamond. Diamonds develop in cratons, the oldest areas of the Earth’s crust, and may come up from such paces to travel down water bodies. As such, you may find the stone in streams, rivers, or the places where flowing water empties into the ocean.
  • Physical tells can also be considered, as the appearance and shape of the crystal surface. Raw diamonds mostly have a coating that looks like Vaseline over them. Plus, they appear with rounded edges with tiny indented angles, while some also come with rotated squares or parallelograms. Also, raw diamonds are known to have cubic structures, meaning you should expect no more than four sides, or what you have is a quartz crystal. And you can check using a 10x loupe, a special magnifying glass employed for observing crystal jewelry, or under a microscope.
  • Diamonds cleave to give a smooth flat surface at their breakage points, so if you find this on the stone, then you may have one. But if you notice conchoidal surfaces on the gem, it’s not a raw diamond.
  • Place the gem under a shortwave ultraviolet light. Many diamonds glow blue under such light (about 30% of them), and if this happens, then you’ve got a real gem. But note that some may produce yellow, orange, or red colors when run through this same process.
  • Heat the gem to check if it breaks, and if it doesn’t, it may be a real diamond. To do it, hold the diamond over a flame for about 40 seconds, and then drop it immediately in cold water. A true raw diamond will hold its form regardless of this procedure, but quartz or other less-durable crystals will shatter. The sudden temperature change causes quick expansion and contraction in the crystal’s structure. And the resultant shock forces it to break.
  • Also, consider a fog test to confirm if the gem is a raw diamond. Do this by holding the stone before your mouth and between your fingers. Then, fog it by breathing out onto the surface, as you would on a mirror. The fog formed on its surface will immediately disperse on a real diamond because they’re impressive heat conductors. But if the fog takes a while to dissipate, it’s likely quartz or some other crystal you found.

Once you’ve confirmed the stone has four sides, you’ll still need more technical tests to be 100% certain you’ve found a raw diamond. And these procedures can help you confirm such suspicion,

1. Run a Hardness Test

Diamonds are also noted as the hardest gemstones, and rate staggering readings on the Mohs scale of hardness- a quantifier that rates minerals from softest to hardness. And you can check if a stone is a raw diamond by using this property. The hardness test is another easy step to confirming if your gem is a raw diamond. And to check, you’ll need to rub the stone against the mineral called corundum.

Corundum includes all sapphires and rubies and rates high on the Mohs scale- nine, to be precise- so it’s a pretty tough material to scratch. So, if your gem scratches this mineral, you may have a raw diamond in hand. But it helps to also try other more advanced tests on the stone, to be sure. The reason is certain scratch-resistant metals exist, such as moissanite and cubic zirconia, and may be confused for raw diamonds because they pass the hardness test.

2. Test for Specific Gravity

One way to confirm if the stone is a raw diamond is to check its specific gravity. This method works by using the ratio of the stone’s density to a pure liquid of thickness of 1g/ml to confirm authenticity. And it’s a reliable method of ensuring that what you’ve found is a raw diamond. But to do it right, follow these steps;

  • Check the stone’s weight on an electric scale, and once gotten, record this number. You’ll want to use an accurate scale, especially one that goes no less than two to three decimal places after the whole number.
  • Next, fill a cup with water so it’s enough to submerge the stone. Ensure the cup isn’t overfilled so the water doesn’t spill. And once done, place this cup of water on the scale and set the reading to zero. A plastic or paper cup works best for this procedure. And you’ll want it properly centered on the scale and not hanging off the edges, so the reading isn’t off.
  • Tie a paper clip around the stone, so you can submerge it without it dropping to the bottom. You want the stone suspended in the cup of water, so ensure that the clip is long enough to hold. 
  • Lower the stone into the cup of water on the scale without touching the bottom or sides. You won’t need to worry about the paper clip’s weight, as it won’t matter in the final reading. Once the crystal is lowered, note the reading on the scale and record it.
  • Calculate the stone’s density by dividing its weight by the weight derived when submerged in the water. You should expect a result close to 3.5 to 3.53g/cm3, which is the average density of diamonds. And anything less than this number means the stone isn’t one. 

Remember that you’re looking for a specific gravity within the 3.5 to 3.53g/ cm3 range. If the result gives you anything around 2.6 to 2.7g/cm3, then you have quartz, not a raw diamond.

3. Check for Thermal Absorption

Diamonds are renowned for being the best head absorbers among all gemstones. And you can use this property to confirm if the crystal you’ve found is the real deal. What it entails is a thermal absorption test that requires a diamond tester. And this handheld tool works by providing a small amount of heat and calculates the stone’s heat absorption time.

Most jewelry stores use the thermal absorption test method, which is why you’ll find diamond testers on their counters. But you can purchase one for this purpose if you prefer to find out by yourself. But when picking, ensure that the tool has a full battery before using, which you can confirm by checking if the green light is on.

To check the thermal absorption of a stone;

  • Turn on the diamond tester, and confirm by checking for a green light indicator.
  • Press the tester’s tip against the suspected stone. A raw diamond will cause it to light up and make a noise. But if it doesn’t, then your suspicion is false.

Ensure to check reviews when buying a diamond tester for thermal absorption tests, as cheaper ones may not provide accurate information. Some of the best products are sold for around $150 to $300, so your best bet is to spend good cash so you purchase a top-quality tool.


It’s easy to get carried away over finding a crystal that resembles a raw diamond. But if you put it through these tests and procedures stated above, you can be certain if you’ve found a valuable stone. The procedures are also straightforward, so you won’t have to worry about being stressed. But if it seems like a lot of work, you’re obliged to seek a professional for a more convincing evaluation.