How to Tell if a Diamond Is Real: Mined, Lab Grown & Simulants Explained

Both mined and lab grown diamonds are real diamonds. The biggest difference is how they are created, not what they are.

For years, shoppers heard that only mined diamonds were real. The truth is different.

Mined diamonds and lab grown diamonds share the same chemical makeup. They have the same crystal structure. They offer the same sparkle and durability.

What they are not is the same as diamond simulants. That group includes stones like cubic zirconia and moissanite. They may look similar at first glance. But they are different materials.

What Does "Real Diamond" Actually Mean?

The phrase "real diamond" causes a lot of confusion. A better way to think about it is this.

There are three main categories.

Both mined and lab grown diamonds are made from carbon. They have the same hardness. Both types display the same fire and brilliance.

Even experienced jewelers need specialized equipment to tell them apart.

How to Tell if a Diamond Is Real at Home

Many home tests exist. Some are helpful. But none should replace a professional evaluation.

Still, they can provide clues.

The Fog Test

Hold the diamond close to your mouth. Breathe on it as you would a mirror. 

Does the fog disappear almost instantly? The stone may be a diamond. If it stays cloudy for several seconds, it could be a simulant.

This works because diamonds disperse heat very quickly. But there is a catch. Some simulants may perform similarly.

The fog test should never be the only test.

The Water Test

Drop the loose stone into a glass of water. A diamond has high density. So, it should sink quickly. Many fake stones float or sink differently.

This test is simple but it is far from perfect. Certain simulants behave the same way.

Look at the Setting

High quality diamonds are usually mounted in precious metals. Look for markings like:

• 14K

• 18K

• Platinum

• 950 Plat

Those marks do not guarantee a diamond. They only suggest quality craftsmanship.

Examine the Stone Closely

Use a jewelry loupe if possible and look for tiny natural inclusions. Many mined diamonds contain small internal features. Lab grown diamonds may also show growth characteristics.

Perfect clarity does not automatically mean a stone is fake. Some diamonds are exceptionally clean.

Mined Diamonds vs. Lab Grown Diamonds vs. Simulants

The differences are found in how the stones are made.

Both mined and lab grown diamonds are genuine diamonds. Simulants simply imitate the appearance.

Can You Tell if a Diamond Is Real Just by Looking?

Most people cannot. Even experienced jewelry lovers struggle without magnification or special tools. A diamond's sparkle is beautiful. But sparkle alone proves very little.

Moissanite reflects light differently. Cubic zirconia can also appear bright under store lighting. That is why appearance should never be the only test.

Common Diamond Myths That Refuse to Go Away

Diamond myths have been around for years. Knowing the facts makes shopping much easier.

Myth: Lab Grown Diamonds Are Fake

Lab grown diamonds are genuine diamonds. They have the same chemical composition as mined diamonds. They also share the same hardness, brilliance, and crystal structure.

The only difference is how they are created.

Myth: Bigger Sparkle Means a Better Diamond

A brighter stone is not always a better stone.

Sparkle depends on the diamond's cut. A well-cut diamond reflects light beautifully. A poorly cut diamond may look dull, even if it is larger.

Myth: Every Diamond Has Flaws You Can See

Many people expect genuine diamonds to have visible marks. That is not true.

Most inclusions are tiny. They often require magnification to see. Some diamonds appear perfectly clean to the naked eye.

Visible flaws are not a requirement for authenticity.

Myth: You Can Always Spot a Diamond by Looking at It

Modern diamond simulants can closely resemble diamonds. It isn’t possible to tell the difference without proper tools.

That is why professional testing remains the most reliable option.

Myth: A Diamond Should Scratch Glass

Diamonds can scratch glass because they are extremely hard. But they are not the only stones that can do it. Moissanite can also scratch glass with ease.

Scratching glass does not prove a stone is a diamond. It can also damage both the stone and the glass. This makes this test a poor choice.

Myth: Diamonds Are Indestructible

Diamonds are the hardest natural material on the Mohs scale. Hardness and toughness are different things.

A diamond resists scratches very well. Still, a hard impact at the right angle can chip or cleave it. That is why jewelers recommend removing diamond jewelry during heavy work or sports.

Myth: Every Genuine Diamond Has a GIA Certificate

A grading report is good. But not every genuine diamond comes with one.

Many authentic diamonds are graded by respected laboratories such as:

• GIA (Gemological Institute of America)

• IGI (International Gemological Institute)

• AGS (American Gem Society)

Some genuine diamonds may not have a grading report at all. This is common for older family heirlooms or smaller stones.

The absence of a GIA certificate does not automatically mean a diamond is not genuine.

When Should You Visit a Professional Jeweler?

Sometimes the smartest answer is the simplest. Ask an expert. Professional jewelers use tools designed for accurate identification.

These may include:

• Diamond testers

• Microscopes

• Magnification loupes

• Certification reports

• Advanced screening equipment

This process removes guesswork. That is important for those who have inherited a family ring. Those shopping for an engagement diamond can also benefit from this. 

How Professional Diamond Testers Work

Most diamond testers measure heat conductivity. Diamonds transfer heat extremely fast. Many common simulants do not. The tester reads that difference. Then, it displays a result within seconds.

This simple technology has helped jewelers identify diamonds for many years.

Single-Probe vs. Dual-Probe Diamond Testers

Not every tester works the same way.

A single-probe tester checks heat only. That works well for many stones. However, moissanite conducts heat much like a diamond. Because of that, a basic tester may identify moissanite as a diamond.

A dual-probe tester solves this problem. It measures both heat and electrical conductivity. Those extra readings help distinguish moissanite from a diamond with much greater accuracy.

Why Moissanite Needs Advanced Testing

Moissanite is one of the closest diamond look-alikes. That is why older thermal testers struggle to tell the difference.

Modern dual testers add electrical conductivity testing to improve accuracy. Many current professional models claim accuracy levels of up to 98% when separating diamonds from moissanite under normal testing conditions.

How HPHT and CVD Screening Equipment Works

Professional gem laboratories and some jewelry stores use specialized systems to screen diamonds.

One well-known example is DiamondView technology. These systems study how a diamond reacts under controlled ultraviolet light.

The patterns can reveal growth features linked to:

• Natural mined diamonds

• HPHT lab grown diamonds

• CVD lab grown diamonds

This level of analysis goes far beyond a handheld tester. It helps experts determine a diamond's origin rather than simply confirming it is a diamond.

Professional Testing Uses More Than One Tool

A jeweler uses several tools to get an accurate picture.

Common equipment includes:

• Diamond testers

• High-powered microscopes

• Jewelry loupes

• Specialized lighting

• Diamond grading reports

• Advanced laboratory screening systems

Each tool provides another piece of information. Together, they create a far more reliable evaluation than any single home test.

Signs You May Be Looking at a Diamond Simulant

Many diamond simulants look stunning. At first glance, even an experienced shopper may struggle to spot a difference. That is why jewelers look beyond appearance.

They study small details that most people never notice.

Cubic Zirconia Signs to Watch For

Cubic zirconia is a common diamond lookalike. But a closer look may reveal a few clues.

Look for:

• Very few or no visible inclusions

• Rounded facet edges from everyday wear

• Surface scratches over time

• A heavier feel than a similar sized diamond

• Softer sparkle with broader flashes of light

Moissanite Signs to Watch For

Moissanite is one of the hardest simulants to identify without special tools.

Watch for:

• Strong rainbow flashes in bright lighting

• More colorful sparkle than many diamonds

• Crisp facet edges that stay sharp

• Excellent clarity with few visible internal features

Even with these clues, visual inspection is not enough. As already mentioned above, moissanite transfers heat similar to a diamond. Thus, many jewelers rely on dual-probe testers. 

Glass and Synthetic Spinel Signs to Watch For

Glass and synthetic spinel still appear in inexpensive fashion jewelry.

Possible signs include:

• Tiny air bubbles inside the stone

• Visible scratches after light wear

• Softer shine instead of sharp brilliance

• Dull facet edges

• Lightweight feel compared to similar gemstones

The "Too Perfect" Look

Natural diamonds formed over millions of years. They contain tiny internal features called inclusions. These microscopic characteristics are usually impossible to see without magnification.

Many mass-produced simulants look fully flawless instead. The stone may appear perfectly clear from edge to edge. Some jewelers describe this as a sterile or almost plastic appearance.

Of course, some genuine diamonds also have exceptional clarity. That is why this observation is only one clue, not a final answer.

Choose Knowledge Before You Choose a Diamond

Buying a diamond should feel exciting, not overwhelming. The best decision starts with accurate information and not outdated myths. 

At Dunkin's Diamonds, education comes before the sale. Our diamond experts take time to explain diamond characteristics and answer questions with transparency. They help shoppers compare mined and lab grown options with confidence.

FAQs

What Is a CVD Diamond?

A CVD diamond is a lab grown diamond created using Chemical Vapor Deposition technology. Carbon atoms build layer by layer until a diamond forms. It has the same chemical composition, hardness, and sparkle as a mined diamond. The main difference is where it comes from, not what it is.

Can Moissanite Pass a Diamond Tester?

It can happen with older thermal diamond testers. Moissanite transfers heat much like a diamond, which may cause a false reading. Modern dual-probe testers measure both heat and electrical conductivity. They are much better at telling moissanite and diamonds apart, although professional testing remains the most reliable option.

How Do I Verify a Diamond Certificate Is Real?

Start by finding the report number on the certificate and the diamond, if it is laser inscribed. Then enter that number on the grading laboratory's official website. The details should match the stone's shape, measurements, and grading information. If anything looks different, ask a trusted jeweler to review it.

Does Lab Grown Mean Lower Quality?

No. Lab grown diamonds can be just as beautiful and durable as mined diamonds. Quality depends on the same factors, including cut, color, clarity, and carat weight. A well-cut lab grown diamond may outperform a poorly cut mined diamond, making quality separate from origin.