How to Tell If a Diamond Is Real or Fake

Diamonds are more than just pretty stones—they’re symbols of love, milestones, and sometimes a big investment. But with so many lookalikes out there, like synthetic diamonds or diamond substitutes, how do you know if it’s a real diamond? Whether you’re eyeing a diamond ring, checking a family heirloom, or wondering about the diamond in question, figuring out whether your diamond is real is key.

Good news: you don’t need to be a diamond expert to get started. Real diamonds have unique traits—like how they bend and refract light or disperse heat rapidly—that set them apart from fakes like moissanite or cubic zirconia. In this guide, we’ll show you easy ways to determine if your diamond is real using at-home tests, plus when to get it professionally tested for peace of mind.

Let’s dive in and help you confirm whether or not your diamond is the real deal!

Why Knowing If It’s a Real Diamond Matters

We get it—diamonds are special. Whether it’s an engagement ring, a gift, or something you inherited, you want to know it’s a diamond, not a fake. Here’s why it’s worth checking the authenticity of your diamond:

• Save Your Wallet: Mistaking a fake for a real one could mean overpaying or losing value when selling.
• Feel Confident: Knowing whether or not a diamond is real ensures your heirloom or gift carries the meaning you expect.
• Spot the Fakes: Diamond substitutes like moissanite or cubic zirconia can look convincing, but they don’t match the durability or sparkle of real diamonds—whether natural or lab-created diamonds.

You don’t need fancy tools to know how to tell if it’s real. Simple tricks, like checking how a diamond reflects light or sinks in water, can reveal a lot. Ready to play detective? Let’s explore some fun and easy tests you can do at home.

Easy At-Home Tests to Check If It’s a Diamond

You don’t need a lab to figure out whether or not your diamond is real. These at-home tests use everyday items to test a diamond’s properties—like its density, heat conductivity, and the way it reflects light. While no single test is 100% foolproof, trying a few together will help you tell if your diamond is likely real or likely not a diamond.

1. Fog Test: Does the Diamond Disperse Heat Rapidly?

• What to Do: Breathe on the stone like you’re fogging up a mirror. Watch how fast the fog clears.
• Real Diamond: The fog vanishes almost instantly because a real diamond will disperse heat rapidly.
• Fake Stone: The fog sticks around for a few seconds (common in fake diamonds like cubic zirconia).
• Why It Works: Diamonds conduct heat like champs, unlike most diamond substitutes.

Quick Tip: This is a great first step, but some fakes, like moissanite, might trick this test. Try others too!

2. Water Test: Will a Real Diamond Sink?

• What to Do: Drop the diamond into a glass of water (works best for a loose diamond).
• Real Diamond: A real diamond will sink fast due to its high density.
• Fake Stone: If it floats or sinks slowly, it’s likely not a diamond.
• Why It Works: Diamonds are super dense (3.52 g/cm³), heavier than most fakes like glass.

Note: Only try this with loose stones—jewelry settings can mess with the results.

3. Light Reflection Test: Watch How Light Reflects

• What to Do: Hold the stone under a bright light or shine a flashlight on it. Notice the quality of the light.
• Real Diamond: Reflects crisp white light (called brilliance) and rainbow-colored light (called fire). A real diamond does this well, creating a stunning sparkle.
• Fake Stone: Might reflect orange-tinted light or look too glassy (common in cubic zirconia).
• Why It Works: Diamonds bend and refract light uniquely due to their high refractive index (2.42). When light strikes the pavilions—the lower, angled parts of the diamond—it creates that iconic sparkle.

Pro Tip: Compare it to a known real diamond to really see the difference.

4. UV Light Test: Does It Glow Under UV Light?

• What to Do: Shine a UV or black light on the stone in a dark room.
• Real Diamond: Some diamonds glow a faint blue under UV light (about 30% do).
• Fake Stone: Might glow yellow, green, or not at all.
• Why It Works: Blue fluorescence is a natural trait in some diamonds, though not all.

Heads-Up: This test isn’t a dealbreaker—some real diamonds don’t glow, and some fakes do. Use it as one clue among many.

5. Dot Test: Can You See a Dot Through a Real Diamond?

• What to Do: Draw a small dot on white paper and place the diamond flat side down over it.
• Real Diamond: You won’t see the dot because a real diamond bends light so much.
• Fake Stone: If you see the dot clearly, it’s not a diamond.
• Why It Works: A diamond’s intense light refraction hides objects underneath, unlike glass or cubic zirconia.

Try This: This works best with round stones. If the diamond shape is different, results might vary.

6. Mirror Test: Check the Reflections

• What to Do: Hold the stone in front of a mirror and look at its reflections.
• Real Diamond: Shows sharp, clean flashes of light, like a diamond should.
• Fake Stone: Reflections look dull, blurry, or flat.
• Why It Works: A real diamond’s precise cut makes its reflections pop.

Note: This one’s subtle, so try it alongside other tests for the best results.

These tests are like a diamond detective kit—combine them to get a clearer picture of whether the stone is a real diamond. If you’re still unsure, it might be time to call in a pro.

Is Your Diamond Ring or Earring Real?

Got a diamond set in a ring or earrings? Testing it is a bit trickier, but the jewelry itself can give you hints. Real diamonds are valuable, so they’re usually paired with high-quality settings like gold or platinum. Here’s how to check:

Look at the Metal and Markings

• What to Check: Peek inside the ring band or earring post for tiny stamps.
  • Gold: Look for 14K, 18K, or 750.
  • Platinum: Look for PT or 950.
• Red Flag: No markings or cheap, flimsy metal? The stone is likely not a diamond.
• Why It Works: Jewelers use strong, valuable metals for real diamonds, whether natural or lab-created diamonds.

Check the Craftsmanship

• What to Look For:
  • Are the prongs tight and evenly placed?
  • Does the stone sit securely without wobbling?
  • Is the metal smooth and polished?
• Red Flag: Loose stones or sloppy work suggest it’s not the real deal.
• Why It Works: Real diamonds, even lab-created ones, get the VIP treatment with careful settings.

Next Step: If the setting looks fishy, take it to a jeweler to test the stone itself. They’ll know how to tell if it’s a diamond.

Real Diamonds vs. Fakes: How to Tell the Difference

Not every sparkly stone is a diamond. Let’s break down the most common diamond substitutes and how they stack up against the real thing, so you’re able to tell the difference.

Cubic Zirconia (CZ)

• What It Is: A cheap, man-made stone used in costume jewelry.
• How to Spot It:
  • Too perfect—no imperfections within the diamond, unlike real ones.
  • Heavier than a diamond (feels denser).
  • Glassy sparkle, sometimes with orange-tinted light.
  • Scratches easily (softer than a diamond).
• Key Difference: CZ looks shiny but lacks the crisp brilliance of a real diamond.

Moissanite

• What It Is: A tough simulant that’s almost as hard as a diamond and sparkles like a diamond.
• How to Spot It:
  • Intense rainbow-colored light (more “disco ball” than a diamond’s elegant fire).
  • Double refraction—facet edges might look doubled under a magnifying glass.
• Key Difference: Separating a diamond from moissanite takes a special tester, as it can fool standard diamond tests.

Glass or Crystal

• What It Is: Low-cost fakes that mimic sparkle.
• How to Spot It:
  • Air bubbles inside (visible with a magnifying glass).
  • Weak, uneven shine.
  • Feels light and chips easily.
• Key Difference: Glass lacks the durability and sparkle of a real diamond.

Lab-Created Diamonds vs. Natural Diamonds

• What to Know: Lab-created diamonds are real diamonds, with the same sparkle, hardness, and chemical makeup as natural diamonds.
• How They Differ: Only their origin (lab vs. earth) sets them apart, affecting price and sentimental value.
• How to Tell: You’ll need a diamond expert with fancy tools (like spectroscopy) to spot the difference.

Bottom Line: Whether it’s natural or lab-created, a real diamond stands out from fakes like moissanite or CZ by its unique sparkle, weight, and toughness.

When to Get Your Diamond Professionally Tested

At-home tests are fun and helpful, but they’re not the final word. If the diamond in question is valuable—say, an engagement ring or a family heirloom—you’ll want to confirm whether it’s a real diamond with a pro. A diamond expert can tell you not just if it’s a diamond, but also its quality (cut, color, clarity, and carat—the 4Cs).

When to Call in a Pro

• Your home tests give mixed results.
• The diamond shape (like pear or emerald) makes tests tricky.
• You’re buying or selling through diamond retailers or private sellers.
• You need to know for insurance or resale.

Tools the Pros Use

• Diamond Tester: Checks heat conductivity to confirm it’s a diamond.
• Moissanite Tester: Spots moissanite, which can trick regular testers.
• 10x Loupe or Microscope: Shows imperfections within the diamond and cut details.
• UV Tools: Checks fluorescence to help identify lab-created vs. natural diamonds.

Why It’s Worth It

A professional can save you from mistaking a $50 fake for a $5,000 real one. In the diamond industry, that’s a big deal! Plus, they’ll give you a report (like from the Gemological Institute of America, or GIA) to prove the authenticity of your diamond.

Pro Tip: Find a certified gemologist or jeweler with GIA credentials. Check out GIA’s website for more on diamond certification.

Red Flags That It’s Not a Diamond

Worried your stone might not be the real deal? Here are some signs it’s likely not a diamond:

• Too Perfect: No tiny flaws or imperfections within the diamond (real ones almost always have some).
• Weird Sparkle: Reflects orange-tinted light or looks overly glassy.
• Cheap Setting: Jewelry has no gold or platinum markings or feels flimsy.
• Feels Off: Stays warm, feels light, or scratches easily.
• Fails Tests: Doesn’t pass fog, water, or light tests.
• No Proof: No GIA or similar certification for a high-value stone.

If you spot a few of these, it’s time to get that diamond professionally tested.

Wrapping It Up: How to Know If Your Diamond Is Real

Wondering whether your diamond is real? You’ve got this! Here’s a quick rundown of how to tell if it’s a real diamond:

• Try These At-Home Tests:
  • Fog Test: Fog clears fast on a real diamond.
  • Water Test: Drop the diamond—it’ll sink if it’s real.
  • Light Test: Watch how light reflects for crisp brilliance and rainbow fire.
  • Dot Test: Can’t see a dot through a real diamond.
  • UV Test: Some diamonds glow under UV light (faint blue is a good sign).
  • Mirror Test: Look for sharp, clear reflections.
• Check Jewelry: Real diamonds come in quality settings like gold or platinum.
• Know the Fakes: Fake diamonds like moissanite or CZ don’t match a real diamond’s sparkle or toughness.
• Get Expert Help: When in doubt, a diamond expert can confirm whether or not your diamond is real.

You don’t have to be a pro to figure out if it’s a diamond. These tests will get you pretty far, and if you’re dealing with something special—like a diamond ring or heirloom—take it to a jeweler for the final say. That way, you’ll know for sure whether your diamond is real and ready to shine.

One Last Tip: Always ask for a GIA or AGS certificate when buying a diamond. It’s the best way to know you’ve got the real deal.