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Do You Think You Found a Diamond? Learn How to Identify Rough Diamonds

Every week I get an email from somebody that thinks they found a diamond. Maybe you are reading this because you think you found a diamond. This article will tell you how, and how not to identify rough diamonds as they are found in nature.

The chances of finding a rough diamond are extremely rare. Odds are you did not find a diamond. First a few questions:

1. Is the suspected diamonds larger than 8 mm (3/8 of an inch)?

2. Does the suspect diamond weigh more than 2 grams (10 carats)?

3. Did you find more than one suspected diamond?

If the answer to any of those questions is YES, then I have bad news - you probably did NOT find a diamond.

Diamonds over 8 mm, in excess of 2 grams in weight are extremely rare. The chances of finding a diamond are 1 in 10,000,000. The chances of finding a diamond over 8 mm, in excess of 2 grams in weight are 1 in 1,000,000,000. That is one chance in a billion!

OK, so you think you beat the odds and actually found a rough diamond. Now how do you test it to confirm it is a diamond?


Crystal Form:

Looking at the crystal form is a quick way of differentiating diamond from most of the other minerals that look like diamond.

Diamonds are cubic (isometric) form. The most common mineral that looks like a diamond is quartz and it is hexagonal form. When looking down on the crystals from the top, with the point of the crystal aimed at your eye, quartz will have six sides and a diamond will have four sides. If you see six sides than you probably found quartz.



When diamonds break, they will cleave creating smooth, flat surfaces. Quartz and glass will create conchoidal surfaces when they break.

If you see curved conchoidal surfaces (see photo above) then you know your sample is not a diamond.


Test Hardness:

You CANNOT test the suspect diamond by scratching glass.

Many minerals scratch glass. Glass is 5.5 on the Moh's Scale of Hardness. The following list is of common minerals that scratch glass, may look like diamond and they are much more common the diamonds:





















So do not try scratching glass with the suspected diamond. The only hardness test that will identify a diamond is scratching corundum. Corundum, which includes all rubys and sapphires, is 9 on the hardiness scale. If your suspected diamond crystal can scratch corundum, then there is a good chance that you found a diamond. But NO OTHER HARDNESS TEST will identify a diamond.

Click here to buy inexpensive corundum crystals for testing diamond hardness.


Test Specific Gravity:

Testing for specific gravity will determine the density of a diamond. Actual diamond has a density of 3.5 - 3.53 g/cm3 and you can use this easy home test for specific gravity at: Simple Specific Gravity Test at Home.

But this test is difficult to perform accurately on small samples. If your sample is large, then you failed the question 1 in the first section. If your sample is small, then the accuracy is poor. So unless you have access to a laboratory scale then I suggest skipping the specific gravity test.


Test for Thermal Absorption:

Diamonds absorb heat better than any other mineral and there are a wide variety of portable diamond testers on the market. Search on Google for "Portable Diamond Tester" and you will find many for sale from $13 to $300. Do NOT buy a cheap tester -- they are made in China and are not very accurate. You should spend around $150 for a good tester.

These diamond testers are hand-held devices with a metal probe that is held in contact with the suspected diamond. It generates a small amount of heat and measures the speed that the heat is absorbed by the crystal. Good testers can differentiate between diamond, moissanite (a common synthetic diamond-simulant), and other minerals.

You do not have to buy a diamond tester. Almost any reputable jeweler will own one, and testing is quick and easy. So try visiting your local jeweler and ask if he will test your suspected diamond.


The odds are against you finding a diamond. But if you are not convinced, first look at the crystal shape to see if it is isometric form, make sure the fracture surfaces are not conchoidal, check if it scratches a corundum crystal. If it passes all of the above, then try a diamond tester to measure thermal absorption.

One final thought...

The odds of finding a diamond are equal to being struck by lightning on your birthday 20 years in a row. Even if you found a real diamond, purchased a diamond tester to verify, nobody will take you seriously. The ONLY way you will convince anybody it is a real diamond is to have it certified by the Gemmological Institute of America (GIA). For a fee they will test your "diamond" and give you a certificate absolutely, positively identifying it as diamond, plus they will give you back the diamond unharmed. With that certificate you will have proof of your find, and buyers will be seriously interested in purchasing your find.

Because a GIA certificate will eventually be required anyway, save your money and do NOT buy a diamond tester. Instead send it straight to the GIA for a certification.





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