How to Tell if a Diamond is Real

When it comes to diamonds, authenticity is paramount. The market is teeming with counterfeit diamonds and low-quality substitutes that can deceive even the most discerning buyer. Knowing how to distinguish the real from the fake not only ensures you’re making a sound investment but also preserves the prestige associated with these remarkable gems. In this blog, we’ll walk you through easy and reliable ways on how to tell if your diamond is real.

Visual Inspection: What Real Diamonds Look Like

Visual inspection forms the first line of defence against fake diamonds. Here’s how to tell a real diamond by eye:

Brilliance

Brilliance refers to how much white light is reflected from and within a diamond. A real diamond’s brilliance appears as bright white and grey flashes of light, creating a bright, sparkling effect. Unlike fakes, which tend to have more intense, artificial-looking rainbow sparkle (fire), a real diamond exudes white brilliance and a subtle rainbow effect.

Facet Quality

Facets are the flat, polished surfaces cut into a diamond to create its shape and magnify its brilliance. Real diamonds have sharp, well-defined, and precisely shaped facets, unlike the rounded or poorly cut facets of imitations. A high-quality diamond cut exhibits excellent symmetry, meaning the facets align perfectly and reflect light symmetrically.

Hardness

Hardness refers to a gemstone’s resistance to scratching. Diamonds are exceptionally hard, ranking a perfect 10 on the Mohs scale of hardness, and are the only naturally occurring mineral with that grade. Imitation diamonds typically rank much lower, making them more susceptible to surface scratches over time.

Refractive Index

The refractive index (RI) measures how much a material bends light that passes through it. The higher the RI is, the more sparkle and brilliance a diamond has. Diamonds have an exceptionally high RI compared to other gemstones, with values ranging from 2.417 to 2.419. Imitation stones often have lower RI, which results in a lack of brilliance and makes them appear dull or glass-like in comparison.

Inclusions

Real diamonds are formed under extreme heat and pressure, creating various imperfections or inclusions. These unique characteristics serve as natural fingerprints, confirming a diamond’s authenticity. Imitation diamonds don’t have the same natural imperfections and may even appear perfectly clear and flawless under magnification.

What You Can Do to Verify Diamond Authenticity

Beyond visual inspection, several tests can further confirm a diamond's authenticity. For a more accurate assessment, it’s best to do a combination of these tests, as a single method alone may not offer conclusive proof.

1. The Fog Test

Diamonds are excellent conductors of heat, meaning they disperse heat quickly. Although the fog test is fairly reliable for a quick assessment, it is not a foolproof method as ambient temperature and humidity can affect the results.

1. Clean the diamond. Ensure the gemstone is clean and free of any oils or dirt.

2. Wear gloves or use tweezers to hold the diamond in place to avoid transferring oils or dirt, which can alter results.

3. Breathe on it. Hold the diamond between your gloved fingers or tweezers and breathe on it to create a light fog on the surface.

4. Observe the fog. If the fog dissipates right away, the diamond is real. If it takes seconds for the fog to disperse, it is likely a fake.
   

2. The Water Test

Diamonds are very dense, meaning they sink in water. However, while this test can be a quick indicator, it is not definitive, as some diamond simulants like cubic zirconia can also sink.

1. Prepare the glass. Fill a clear glass or cup about three-quarters full with clean water.

2. Isolate the stone. Ensure the diamond is loose and not set in any metal, as it can affect the results.

3. Drop the stone into the water. A real diamond should sink to the bottom of the glass. If it floats or stays near the surface, it’s likely not a real diamond.

3. The Heat Test

Real diamonds won’t crack or shatter when exposed to rapid heat transfer, unlike weak materials like cubic zirconia. However, this test should only be performed on loose stones, not on mounted jewellery, as the heat can damage the setting or surrounding materials.

1. Gather your materials. You’ll need a lighter, a pair of metal tweezers, and a glass of cold water.

2. Secure the diamond. Use the tweezers to firmly hold the diamond.

3. Apply heat. Heat the diamond evenly with the lighter for approximately 30-45 seconds. Remember to always take proper safety precautions and do this only in safe, well-ventilated areas away from flammable materials.

4. Immediately drop the diamond into the cold water. If the diamond remains intact and shows no cracks or damage, it is likely a real diamond.

4. UV Light Test

When exposed to UV light, a diamond can show nonexistent to very strong fluorescence. Generally, a real one often shows some degree of blue fluorescence, which can help distinguish fake vs. real diamonds under UV light.

1. Find a UV light source. It can be a black light, strong sunlight, or a specialised diamond tester with a UV light.

2. Position the diamond. It should be directly under the UV light source.

3. Observe the glow. Most real diamonds will emit a blue coloured glow, while others may not glow at all. Keep in mind that some fake diamonds can also glow under UV light, so this shouldn’t be taken as a definitive test.

5. The Newspaper Test

A real diamond has high refractive and reflective properties, meaning it bends and scatters light in multiple directions. This makes it difficult to see through the stone and read the text. Remember that this method is best applied for loose diamonds.

1. Gather your materials. You’ll need a piece of newspaper with text and the diamond you want to test. Ensure the diamond is clean and free of any debris that might interfere with the test.

2. Lay the newspaper flat. Choose a section of the newspaper with clear, printed text and place it on a flat, stable surface.

3. Place the diamond. Carefully position the diamond flat side down directly on top of the text. If you can easily read the letters or see them clearly, the diamond is likely a fake.

6. The Dot Test

Similar to the newspaper test, this method evaluates the diamond’s light-bending properties. This works for round, transparent stones, especially when loose.

1. Prepare the surface. You’ll need a piece of white paper and a pen or marker.

2. Draw a dot. Make a small, dark dot in the centre of the paper.

3. Place the diamond directly over the dot. If you can clearly see the dot or a circular reflection, the diamond is likely a fake. If it appears distorted or blurry, it is likely real.

How to Tell a Real Diamond from Moissanite

Moissanite is a lab-created gemstone made from silicon carbide. To the untrained eye, Moissanite can closely resemble the look of a real diamond, making it one of the most popular (and convincing) diamond simulants available. Some of the key differences are:

• Brilliance and Fire: A real diamond has a more subdued sparkle, while moissanite tends to have more intense sparkle and fire (rainbow flashes of light) than diamonds, especially in larger stones. This "disco ball" effect is a key visual difference.

• Hardness: While very durable, moissanite ranks slightly lower on the Mohs scale (9.25) compared to diamonds (10). This makes diamonds more resistant to scratches over time.

• Double Refraction: Moissanite displays double refraction, which means you may see a doubled facet edge when looking through the stone at certain angles. Diamonds do not have this property.

If you're ever in doubt, consult a jeweller or gemmologist equipped with professional tools to distinguish between the two. For a more in-depth comparison, visit our Diamond vs. Moissanite guide.

How to Tell a Real Diamond from Cubic Zirconia

Cubic zirconia (CZ) and real diamonds, while visually similar, differ significantly in their composition, durability, and brilliance. Diamonds are naturally occurring carbon crystals, while CZ is a man-made simulant composed of zirconium dioxide. Some of the key differences are:

• Hardness: CZ is much softer than diamonds, ranking 8 to 8.5 on the Mohs scale. It is also more prone to scratching and losing its lustre over time.

• Inclusions: Most natural diamonds have minor inclusions (flaws). CZ stones are typically flawless, which can make them easier to distinguish from real diamonds.

• Brilliance and Fire: Diamonds exhibit a brilliant sparkle with white light reflections and subtle flashes of colour (fire). CZ tends to show more prominent rainbow-like flashes of colour, which can look more artificial.

Natural vs. Lab-Grown Diamonds

Lab-grown diamonds are essentially the same in terms of chemical composition, physical properties, and appearance as natural diamonds. So, yes, lab-grown diamonds are real diamonds. The key difference between lab diamonds vs. natural diamonds lies in their origin: natural diamonds are mined from the earth and are formed over billions of years, while lab-grown diamonds are created in a controlled laboratory environment, typically over just a few weeks. Additionally, lab-grown diamonds typically offer better value at a lower price point, while natural diamonds carry geological rarity.

Can you tell them apart? Not with the naked eye. Even trained gemmologists cannot distinguish a lab-grown diamond from a natural one without specialised tools. Both types of diamonds are also graded and certified by the GIA (Gemological Institute of America) or IGI (International Gemological Institute), ensuring transparency and trust for buyers.

How to Tell if Your Diamond Jewellery Is Real

Ensuring the authenticity of diamond jewellery involves examining the quality of metals, prongs, links, clasps, and settings. Here’s how:

Diamond Rings

For diamond rings, knowing how to tell if a diamond ring is real starts with inspecting the quality of the setting. Real diamonds are typically set in high-quality precious metals like platinum, 18ct yellow gold, 18ct rose gold, and 18ct white gold. The setting should be symmetrical, secure, and neatly crafted. Prongs holding the stone should grip it firmly without bending or looseness. Poor craftsmanship or plating that wears away quickly are common red flags for fake stones or lower-end imitation jewellery.

Diamond Earrings

For diamond earrings, pay close attention to the earring backs and posts. The mountings should be solid, with no signs of glue or asymmetry. Real diamond earrings can also often feel heavier due to both the stone and the metal. Light, flimsy construction may indicate costume jewellery or imitation stones.

Diamond Bracelets

Diamond bracelets, particularly tennis bracelets, should exhibit consistent stone placement, sturdy clasps, and high-quality links. Each diamond should be securely mounted in identical settings, aligned in a seamless pattern. Real diamond bracelets often feature double-locking clasps for added security, a detail usually absent in cheaper imitations. Also, inspect the metal markings near the clasp for carat stamps or hallmark identifiers.

Diamond Necklaces

When it comes to diamond necklaces, authenticity reveals itself in the details: chain quality, pendant setting, and clasp construction. Authentic diamond necklaces will have precisely cut stones with clean, secure bezel or prong settings. The chain should be made from solid precious metals with a hallmark stamp, and the clasp should feel durable, often featuring lobster clasps or spring rings made of gold or platinum. Be wary of any chain that tarnishes quickly or settings that look glued.

How to Ensure You’re Buying the Real Thing

Here's how to ensure the diamond you’re buying is genuinely worth the investment:

1. Buy from a Reputable Jeweller

A long-standing reputation for quality and integrity is your first layer of protection against buying a fake or substandard diamond. Don’t hesitate to ask about a jeweller’s GIA or IGI certifications and experience. In Australia, DX Diamonds is a trusted name known for its transparency, ethical sourcing, and expert craftsmanship. For over 120 years, the brand has helped generations of customers find authentic, high-quality diamonds with confidence. With a carefully curated selection of certified natural and lab-grown diamonds, DX Diamonds provides detailed grading reports and personalised guidance to help you make an informed purchase.

2. Request a GIA Certification

The Gemological Institute of America (GIA) provides certifications confirming a diamond’s authenticity and quality. Don’t settle for verbal assurances. If the jeweller can’t provide certification from the GIA, IGI, or a similarly respected institution, that’s a red flag.

3. Be Wary of ‘Too Good to Be True’ Prices

While everyone loves a good deal, diamonds priced significantly below market value should raise suspicion. Counterfeit diamonds, poorly cut stones, or diamonds with undisclosed treatments are often disguised as bargains. If a stone is discounted, ask: Is it due to a lower clarity grade, visible inclusions, or a synthetic origin? Remember, price should reflect quality, especially when it comes to the 4Cs.

4. Educate Yourself Before Buying

Knowledge is your best defence. Understanding the 4Cs, cut, clarity, colour, and carat weight, will help you assess whether a diamond is worth its price tag. Educating yourself also means understanding which certifications truly matter and knowing how to tell if a diamond is real.

Think You’ve Found the One?

When it comes to something this meaningful and important, real is always worth it. While imitation diamonds may offer short-term allure, they lack the brilliance and enduring value of a real diamond. Before finalising your purchase, take the time to verify its authenticity through trusted methods and certifications. And when you've found the one that meets all those standards, you’ll know it’s not just beautiful: it’s real.

FAQs

1. Can I test a diamond with my phone?

No, a phone cannot reliably test if a diamond is real. Phones don't have the specialised sensors and software to analyse a diamond's properties, which are crucial for accurate identification. Additionally, apps often rely on basic visual tests or user input, which can be misleading and easily fooled by clever imitations.

2. How to tell if a diamond is real with a flashlight?

Shine the light directly onto the stone. A real diamond will reflect white light brilliantly and also exhibit a rainbow of colours due to light dispersion. If the reflections are dull, mostly grey, or the stone doesn't sparkle much, it might be a fake.

3. Will a fake diamond scratch glass?

Yes, a fake diamond can scratch glass, as some common diamond simulants like cubic zirconia and moissanite are hard enough to do so.

4. Can a jeweller tell if my diamond is real?

Yes, an expert jeweller can typically tell if your diamond is real using professional tools and techniques. Our jewellers at DX Diamonds have access to specialised equipment like diamond testers that measure thermal conductivity, which is a key property of real diamonds.

5. Do real diamonds sparkle under light?

Yes, real diamonds sparkle under light. This sparkle, known as scintillation, is a result of the way light interacts with the diamond's facets, producing both brilliance (white light reflection) and fire (coloured light refraction). The quality of the sparkle depends on the diamond's cut, clarity, and how it's maintained.