How to Identify Raw Diamonds: A Comprehensive Guide
Identifying raw diamonds can be a fascinating but challenging endeavor. Unlike their polished and sparkling counterparts, raw diamonds often appear unassuming, resembling ordinary rocks or glass. However, with the right knowledge and tools, you can learn to distinguish these valuable gems from less precious materials. This comprehensive guide will walk you through the essential steps and characteristics to look for when identifying raw diamonds.
## What is a Raw Diamond?
Before delving into the identification process, it’s crucial to understand what a raw diamond actually is. A raw diamond, also known as an uncut or rough diamond, is a diamond in its natural state, as it comes directly from the earth. It hasn’t been subjected to any cutting, polishing, or other treatments that give finished diamonds their brilliance and sparkle. Therefore, raw diamonds lack the characteristic facets and luster of polished gems. They may appear dull, greasy, or even opaque.
Raw diamonds are found in various shapes and sizes, depending on their geological origin and the conditions under which they formed. They can range from tiny microdiamonds to large, impressive stones weighing hundreds of carats. Their color can also vary, ranging from colorless to yellow, brown, gray, and even rarer colors like pink, blue, and green. The presence of inclusions (internal imperfections) and blemishes (surface imperfections) is common in raw diamonds.
## Why Identify Raw Diamonds?
There are several reasons why you might want to learn how to identify raw diamonds:
* **Prospecting:** If you are interested in prospecting for diamonds in known diamond-bearing areas, knowing how to identify them is essential for recognizing potentially valuable finds.
* **Investment:** Raw diamonds can be an investment opportunity, although it’s a complex market requiring expertise and careful evaluation. Identifying genuine raw diamonds is crucial to avoid scams and make informed decisions.
* **Gemology Enthusiast:** Learning about gemology and the characteristics of raw diamonds can be a rewarding hobby for anyone interested in the science and beauty of gemstones.
* **Jewelry Making:** Some jewelers and artisans prefer to work with raw diamonds to create unique and rustic pieces that highlight the natural beauty of the stones.
## Tools and Equipment You’ll Need
To accurately identify raw diamonds, you’ll need the following tools and equipment:
* **Magnifying Glass or Jeweler’s Loupe (10x or higher):** This is essential for examining the surface features, inclusions, and other details of the stone.
* **Bright Light Source:** A strong, focused light source will help you see the stone’s internal characteristics and transparency.
* **Hardness Testing Kit (Optional):** This kit includes minerals of known hardness, allowing you to test the stone’s hardness against the Mohs scale.
* **Density Testing Kit (Optional):** This kit allows you to measure the specific gravity (density) of the stone, which can help differentiate it from other materials.
* **Diamond Tester (Optional):** Electronic diamond testers measure the thermal conductivity of a stone. Diamonds conduct heat very efficiently. However, these testers are not foolproof and can be fooled by other materials, such as moissanite.
* **Tweezers:** For handling the stones without contaminating them with fingerprints.
* **Clean Cloth:** For wiping the stone and removing any dirt or debris.
## Steps to Identify Raw Diamonds
Follow these steps to systematically assess a potential raw diamond:
### 1. Visual Inspection
The first step is to carefully examine the stone with your naked eye and then with a magnifying glass or jeweler’s loupe. Look for the following characteristics:
* **Shape:** Raw diamonds often have distinctive shapes. Common forms include:
* **Octahedral:** This is the most common crystal shape for diamonds, resembling two pyramids joined at their bases. The faces are often slightly rounded or distorted.
* **Dodecahedral:** This shape has twelve faces, each of which is a pentagon. These are less common than octahedrons.
* **Cubic:** Cubic diamonds are relatively rare but can occur. They have six square faces.
* **Irregular:** Many raw diamonds don’t have perfectly formed crystal shapes and may appear as irregular lumps or fragments. Look for curved faces, trigons (triangular depressions), or other distinctive features.
* **Surface Texture:** The surface of a raw diamond can vary. Look for:
* **Adamantine Luster:** This is a unique, brilliant luster that is characteristic of diamonds. It’s not always easy to see in raw diamonds, but look for any hint of a bright, reflective surface.
* **Greasy or Waxy Luster:** Some raw diamonds have a slightly greasy or waxy appearance.
* **Etch Marks and Trigons:** Trigons are small, triangular depressions that can be found on the surface of diamonds. They are a strong indicator of a diamond.
* **Rounded Edges:** Raw diamonds often have rounded edges due to abrasion during their journey from the mantle to the earth’s surface.
* **Color:** Raw diamonds can come in various colors. Common colors include:
* **Colorless to Near Colorless:** These are the most valuable diamonds.
* **Yellow or Brown:** These are common colors for raw diamonds.
* **Gray:** Gray diamonds are also relatively common.
* **Fancy Colors:** Rare colors like pink, blue, green, and red can significantly increase a diamond’s value.
* **Transparency:** While polished diamonds are known for their transparency, raw diamonds can range from transparent to opaque. Some raw diamonds may appear cloudy or milky.
### 2. Hardness Test
Diamonds are the hardest naturally occurring material on Earth, with a Mohs hardness of 10. This extreme hardness is a key characteristic that can help distinguish them from other minerals.
* **Scratch Test:** Carefully try to scratch the suspect stone with a mineral of known hardness, such as quartz (Mohs hardness of 7). If the stone scratches the quartz, it is harder than 7. If the quartz scratches the stone, it is softer than 7. A diamond will scratch almost any other material.
* **Caution:** Be very careful when performing scratch tests, as you can damage the stone. Only perform this test if you are reasonably certain that the stone is a diamond and are willing to risk minor damage.
### 3. Density Test (Specific Gravity)
The specific gravity (SG) of a diamond is approximately 3.52. This means that a diamond is 3.52 times denser than water. You can measure the specific gravity of a stone using a density testing kit.
* **Procedure:** Weigh the stone in air and then weigh it while submerged in water. Use the following formula to calculate the specific gravity:
SG = Weight in air / (Weight in air – Weight in water)
* **Interpretation:** If the specific gravity is close to 3.52, it supports the possibility that the stone is a diamond. However, some other minerals have similar densities, so this test should be used in conjunction with other identification methods.
### 4. Thermal Conductivity Test
Diamonds are excellent conductors of heat. A diamond tester measures the rate at which heat passes through a stone. If the stone conducts heat rapidly, the tester will indicate that it is likely a diamond.
* **Procedure:** Follow the instructions provided with your diamond tester. Typically, you will need to clean the stone and allow it to reach room temperature. Then, touch the probe of the tester to the stone and observe the reading.
* **Limitations:** Diamond testers can be fooled by other materials, such as moissanite, which also has high thermal conductivity. Therefore, it’s essential to use this test in combination with other identification methods.
### 5. Observation of Inclusions
Most diamonds contain internal imperfections called inclusions. These inclusions can be small crystals, fractures, or other minerals trapped within the diamond during its formation. While inclusions can affect the clarity grade of a polished diamond, they can also be helpful in identifying raw diamonds.
* **Types of Inclusions:** Common types of inclusions in diamonds include:
* **Carbon Spots:** Small, dark spots of un-crystallized carbon.
* **Crystals:** Tiny crystals of other minerals, such as garnet, olivine, or chromite.
* **Fractures:** Small cracks or breaks within the diamond.
* **Feathers:** Feather-like inclusions that can appear iridescent.
* **Using Inclusions for Identification:** Examine the inclusions under magnification. The type, shape, and distribution of inclusions can provide clues about the origin and identity of the stone. Some inclusions are unique to diamonds and can be used as definitive identification markers.
### 6. Hydrostatic Weighing
This is a more accurate method of density determination than using a simple density kit. It requires more specialized equipment, including a hydrostatic balance. The principle is the same as the density test, but the hydrostatic balance provides more precise measurements of the stone’s weight in air and water.
* **Procedure:** Use a hydrostatic balance to measure the weight of the stone in air and water. Calculate the specific gravity using the formula mentioned earlier. The more accurate measurements will result in a more reliable specific gravity value.
### 7. Refractive Index (RI) – Not Applicable for Raw Diamonds
The refractive index (RI) is a measure of how much light bends when it enters a material. Diamonds have a high refractive index (2.417 – 2.419). However, measuring the refractive index requires a polished surface, so this test is not applicable to raw diamonds.
### 8. Seek Expert Opinion
If you are unsure about the identity of a raw diamond, it’s always best to seek the opinion of a qualified gemologist or diamond expert. They have the knowledge, experience, and equipment to accurately identify and assess the value of raw diamonds.
* **Gemological Laboratories:** Submit the stone to a reputable gemological laboratory, such as the Gemological Institute of America (GIA) or the American Gem Society (AGS), for identification and grading.
* **Independent Appraisers:** Consult with an independent gem and jewelry appraiser who specializes in diamonds. They can provide an unbiased assessment of the stone’s identity and value.
## Common Minerals Mistaken for Raw Diamonds
Several minerals can be mistaken for raw diamonds due to their similar appearance. Here are some of the most common:
* **Quartz:** Quartz is a common mineral that can resemble raw diamonds. However, quartz is much softer than diamond (Mohs hardness of 7) and has a lower density.
* **Topaz:** Topaz can also be mistaken for diamonds. It is harder than quartz (Mohs hardness of 8) but still softer than diamond. Topaz also has a different crystal structure and refractive index.
* **Zircon:** Zircon is a mineral that can have a high refractive index and sparkle, but its hardness (Mohs hardness of 6.5-7.5) is much lower than that of diamond.
* **Moissanite:** Moissanite is a synthetic gemstone that is often used as a diamond simulant. It has a high refractive index and thermal conductivity, which can fool some diamond testers. However, moissanite has a slightly different sparkle and can be distinguished from diamonds by its birefringence (double refraction).
* **Glass:** Glass can sometimes resemble raw diamonds, especially if it has been cut or shaped. However, glass is much softer than diamond and has a lower density and refractive index.
* **Rutile:** Can sometimes resemble rough diamonds due to its adamantine luster. However, rutile is significantly softer.
## Conclusion
Identifying raw diamonds requires a combination of visual observation, physical testing, and expert knowledge. By carefully examining the stone’s shape, surface texture, color, hardness, density, and inclusions, you can increase your chances of correctly identifying a raw diamond. However, it’s always best to seek the opinion of a qualified gemologist or diamond expert if you are unsure. With practice and patience, you can develop your skills in identifying these valuable and fascinating gemstones.