Whether you’ve inherited a family heirloom, received a gift, or spotted a discounted offer on a ring, you’ll want to be sure your diamond is genuine before making a purchase. Especially if you’re investing in it or passing it onto family. While only a gemologist is qualified to grade diamonds and gemstones and know the difference, these seven reliable methods will give you a better indication of a real diamond, and all without specialised equipment.
Professional Appraisal & Certification
For absolute certainty, seek a professional appraisal or require a gemological certificate from a recognised lab (GIA, IGI, HRD). Certified diamonds come with a detailed report covering cut, colour, clarity, carat weight, and confirmation of authenticity. This is essential for insurance, resale, or high-value purchases.
Loupe Inspection
A 10× jeweller’s loupe or smartphone macro lens allows you to examine the diamond’s internal and external features. The majority of natural diamonds contain tiny inclusions or imperfections inside the stone, If the diamond is graded less that VVS2 Clarity this is a great way to check your diamond with a loupe. Above VVS2 to flawless diamonds will not show these or you will struggle to find the minimal inclusions present, this is not an indicator in these grades that the stone is not real. Look for sharp facet junctions—real diamonds have crisp, well-defined straight lines on facets and their edges, other stones may not have this level of detail in the cut. Additionally, certified diamonds will state if they have a laser inscription written on the girdle on the diamond, this can give you peace of mind when you can see the certificate number laser inscribed on the diamond showing it matches the certificate and comes up on the report check on that diamond laboratories website as a registered diamond certificate, this is the best question to ask when purchasing a diamond, ask your jewellers does it come with a certificate? and is it laser inscribed? Then ask to use a 10x magnifying loupe to read the inscription. then check this number on that laboratory's website for authenticity that it is a diamond.
Juiletta Single Stone Crossover Diamond Ring
Fog Test
Start with the fog test, which relies on a diamond’s exceptional thermal conductivity. Hold the stone a few centimetres from your mouth and exhale gently so that it becomes fogged, much like breathing on a mirror. A real diamond disperses heat almost instantly, so the fog should clear within one to two seconds. If the fog lingers longer than this, the stone could potentially be a diamond simulant such as cubic zirconia or glass.
Water Test
Next, try the water test on a loose stone (if not set in a jewellery setting). Fill a clear glass with room-temperature water and drop the diamond in gently. Due to its high density (around 3.5 g/cm³), a genuine diamond will sink quickly to the bottom. Many imitations tend to float or sink slowly, making this a useful initial check. Bear in mind that some stimulants, like moissanite, also sink, so pair this with another method for certainty.
Willow Single Stone Shoulder Set Diamond Ring
Light Reflection
Shine a bright white light (an LED lamp works well) onto the stone and observe its reflections on a sheet of white paper. A real diamond reflects a balanced mix of white light (brilliance) and rainbow flashes (fire). In contrast, many fakes display predominantly rainbow colours without the same level of white sparkle. Performing this test in a dim room enhances visibility of the light patterns.
UV (Black) Light Test
Under a UV or black light, many real diamonds exhibit a faint to strong blue colour called fluorescence from inside the stone. Although absence of this blue light does not mean the stone is fake, some diamonds are graded to have no fluorescence within the stone and these are highly valuable and rare diamonds. Simulants and treated stones often show strong green, yellow, or no fluorescence at all. While this test isn’t conclusive on its own, unusual fluorescence colours can indicate when it is not a real diamond.
Electronic Diamond Tester
An electronic diamond tester measures thermal conductivity by touching the stone’s surface with a small needle sized probe. Because diamonds conduct heat exceptionally well, a positive reading confirms authenticity. However, moissanite also conducts heat similarly, so if you suspect moissanite you’ll need a tester designed specifically to distinguish between the two stones.
Combining Tests for Confidence
No single home test is foolproof. To be most effective, combine at least three methods—such as fog, loupe inspection, and electronic testing—before making final judgments. If any result is inconclusive, a professional check is the best next step.
Whether you’re shopping for a new diamond or verifying an inherited piece, these practical tests will help you tell if your diamond is real. And if you need expert assistance. Diamond Quarter’s Jewellery Quarter showroom offers complimentary authenticity checks and professional guidance on all of our stock items. Visit us in person to browse over our certified loose diamonds and we can assist you, showing you the laser inscription, certificate, and explaining the best ways to buy with confidence.