You've inherited a piece of jewellery or found one you're considering buying. You want to know: is this real?
Authenticity matters. Real gold, platinum, and genuine diamonds have value—both monetary and sentimental. Counterfeits and substitutes deceive, disappoint, and can damage your trust. Learning to spot authenticity is essential.
Gold: The Most Common Metal
Gold jewellery is either solid gold, gold-filled, gold-plated, or not gold at all. There's a big difference.
Hallmarks and Stamps
The most reliable indicator is the hallmark—a stamped mark that indicates purity.
What to look for:
- 10K: 10 karat gold; 41.7% pure gold. Most durable; pale colour.
- 14K: 14 karat gold; 58.3% pure gold. The sweet spot—durable and richly coloured.
- 18K: 18 karat gold; 75% pure gold. Richer colour; softer than 14K.
- 22K: 22 karat gold; 91.7% pure gold. Very soft; rare in jewellery.
- 24K: 24 karat gold; 99.9% pure gold. Too soft for everyday wear; used in coins and bullion.
In South Africa and Europe, look for these exact marks stamped on the metal. In the US, you'll see "10K," "14K," "18K" or sometimes just "585" (14K), "750" (18K), etc.
Fake hallmarks: Counterfeits sometimes stamp hallmarks on low-quality metal. This is why hallmarks alone aren't foolproof. Combined with other checks, they're reliable.
Magnetic Test
Gold is non-magnetic. A neodymium magnet (very strong) shouldn't attract gold.
How to do it:
- Get a strong neodymium magnet (online or at hardware stores)
- Hold it near the piece—don't let it touch
- Gold won't move toward the magnet
Caveat: Some alloys mixed with gold are weakly magnetic. A weak response isn't definitive—it just means further testing is needed.
Weight and Feel
Real gold feels substantial. It's dense.
What to compare:
- A real 14K gold ring feels heavier than you'd expect for its size
- A counterfeit gold-plated piece feels light and insubstantial
- Hold a known real gold piece in one hand and the suspect piece in the other—real gold is noticeably heavier
This isn't scientific, but it's a quick initial check.
Specific Gravity Test (The Water Displacement Method)
This is more technical but highly reliable for larger pieces like bracelets.
What you need:
- A digital scale (accurate to 0.1 grams)
- A glass of water
- A string or fishing line
How to do it:
- Weigh the piece in air (note the weight)
- Suspend the piece from a string and submerge it in water without the string touching the water
- Weigh the piece underwater (note the weight)
- Calculate: Air weight ÷ (Air weight – Underwater weight) = Specific gravity
Expected results:
- 14K gold: Specific gravity around 12.5–13.0
- 18K gold: Specific gravity around 13.5–15.0
- Gold-plated over copper: Much lower (around 8–9)
If the specific gravity is significantly lower than expected, it's not solid gold.
Acid Test (Professional Only)
Gold reacts predictably to different acids depending on purity. This is the definitive test, but it should only be done by professionals (like Pura) because it requires strong acids.
Jewellers use a touchstone and acids to determine exact purity. If you suspect a piece and want certainty, bring it to a professional.
X-Ray Fluorescence (XRF)
Modern jewellers use XRF machines—non-destructive, non-invasive, and accurate. The machine reads the elemental composition and determines exact purity in seconds.
At Pura, we have access to XRF testing. It's the gold standard for verification.
Platinum: The Precious Metal
Platinum is rarer and more valuable than gold. It's also much heavier.
Hallmarks
Look for:
- 950: 95% pure platinum; the standard
- 900: 90% pure platinum
- 850: 85% pure platinum (less common)
- Pt, Plat, or Platinum stamped directly on the piece
European marks sometimes show "950" without the word "Platinum," but it refers to platinum if the hallmark is in a specific location.
Weight
This is the biggest tell. Platinum is incredibly dense—about twice as heavy as gold.
A platinum ring feels substantially heavier than a gold ring of similar size. If a ring claiming to be platinum feels light, it's not.
Quick comparison: A 14K gold ring weighs around 5–8 grams. A platinum ring of the same size weighs 12–15 grams. The difference is unmistakable.
Magnetic Test
Platinum is non-magnetic, just like gold. A neodymium magnet shouldn't attract it.
Specific Gravity Test
Platinum has a specific gravity around 21.45. It's much denser than gold.
If you do the water displacement test and get a specific gravity in the 20+ range, it's likely platinum.
Colour
Platinum is naturally white and silvery. It doesn't need rhodium plating to look white (unlike white gold).
- Platinum: Naturally bright white with a distinctive silver tone
- White gold (14K or 18K): Pale yellow under the rhodium plating; plating can wear away
- Silver: Shinier but softer; tarnishes easily
Real platinum has a subtle coolness to its appearance. Once you've seen it next to white gold, the difference is obvious.
Rarity and Cost
Platinum is rarer than gold. A platinum ring costs significantly more than a comparable gold ring.
If you're looking at something claiming to be platinum but priced like white gold, be sceptical.
Diamonds: The Four Cs and Beyond
Real diamonds have specific optical and physical properties that synthetics and simulants don't.
Diamond vs Cubic Zirconia vs Moissanite
The three most common diamond comparisons:
Real Diamond:
- Hardness: 10 (Mohs scale)—the hardest natural substance
- Refraction: Subtle; shows white sparkle with hints of rainbow fire
- Specific gravity: Around 3.5
- Thermal conductivity: Conducts heat rapidly; diamond testers rely on this
Cubic Zirconia (CZ):
- Hardness: 8–8.5; softer than diamond
- Refraction: Excessive rainbow fire; looks "too sparkly"
- Specific gravity: Around 5.9; much heavier than diamond
- Clouding: Clouds and scratches easily; loses sparkle quickly (months to a few years)
Moissanite:
- Hardness: 9.25; nearly as hard as diamond
- Refraction: Shows "double refraction" under magnification; optical effect diamonds don't have
- Specific gravity: Around 3.21; similar to diamond
- Durability: Excellent; doesn't cloud
- Cost: More expensive than CZ, less than diamond
Diamond Testers
Thermal conductivity testers are the most accessible at-home test. They work by measuring how quickly heat conducts through the stone.
How they work:
- Place the device's probe against the stone
- Real diamonds conduct heat away rapidly, triggering a response
- Simulants conduct heat differently, often showing "fail"
Caveat: Moissanite sometimes tests as "diamond" on basic testers because its thermal conductivity is similar. High-quality diamond testers distinguish between them.
Visual Inspection Under Magnification
Under 10x magnification (using a jeweller's loupe), real diamonds show specific characteristics:
- Inclusions: Internal flaws (perfectly normal; rare diamonds are "eye-clean")
- Facet perfection: Facet edges are sharp and precise
- Refraction: Light is refracted in a subtle, natural way
Cubic zirconia under magnification shows:
- Clouding: Often visible, especially on older pieces
- Facet rounding: Edges dull over time as the material scratches
- Excessive fire: Rainbow sparkles that are overdone
Specific Gravity (For Loose Stones)
Using the water displacement method, real diamonds have a specific gravity around 3.5. CZ is about 5.9 (noticeably heavier).
Certificate
The gold standard. A GIA, HRD, or AGS certificate is proof of authenticity. For any diamond over 0.5 carats, insist on it.
The certificate includes:
- A unique report number laser-inscribed on the stone
- The four Cs (carat, colour, clarity, cut)
- A detailed plot diagram
No certificate doesn't mean the diamond is fake, but it means you can't verify it definitively.
Professional Assessment
If you're uncertain, bring the stone to a professional jeweller or laboratory. They have:
- Thermal conductivity testers
- Microscopes for detailed inspection
- XRF machines (which read elemental composition)
- Diamond scales
- Certified expertise
At Pura, we can authenticate diamonds and provide certification referrals.
Gemstones: Beyond Diamonds
Real gemstones—sapphires, rubies, emeralds, etc.—have specific properties.
Hallmarks Don't Apply to Stones
Unlike metals, stones aren't stamped. You need visual and physical checks.
Colour and Saturation
Real gemstones have deep, natural colour. Synthetic or treated stones sometimes show unnaturally vivid or flat colour.
- Real ruby: Deep red with slight variations in tone
- Synthetic ruby: Unnaturally uniform, almost fluorescent red
- Real sapphire: Rich blue with subtle depth
- Synthetic sapphire: Often too bright or too uniform
This is subjective, so combined with other tests, it's more reliable.
Specific Gravity
Different gemstones have different densities:
- Ruby: 3.97
- Sapphire: 3.99
- Emerald: 2.76
- Cubic zirconia (sometimes used as substitute): 5.9
Using the water displacement method, you can estimate whether a stone matches its claimed identity.
Heat and Pressure Testing
Some gemstones are heat-treated or irradiated to improve colour or clarity. This is disclosed by reputable sellers. Undisclosed treatment is a red flag.
A gemologist can detect most treatments using specialized equipment.
Inclusions
Real gemstones typically have inclusions (flaws). Completely flawless gemstones are rare and expensive.
If a "ruby" or "emerald" is perfectly flawless, it may be synthetic or treated. Under magnification, real stones show natural inclusions.
Refraction
Each gemstone bends light in a specific way. A jeweller's refractometer measures this and can definitively identify the stone type.
Professional Gemology
For valuable gemstones (especially coloured stones), professional gemological assessment is recommended. It includes:
- Visual inspection under magnification
- Refractometry
- Specific gravity testing
- Heat/pressure treatment detection
A gemological report from a certified gemologist is your assurance.
Silver: The Softer Metal
Silver is often overlooked, but authenticity matters here too.
Hallmarks
Look for:
- 925: 92.5% pure silver (Sterling silver)
- 950: 95% pure silver
- Ag: Silver
Tarnish
Real silver tarnishes (oxidizes) over time, developing a dark patina. This is normal and expected.
Fake silver doesn't tarnish or tarnishes differently (e.g., turning greenish rather than black).
Magnet Test
Silver is non-magnetic. A neodymium magnet shouldn't attract it.
Acid Test
Silver reacts predictably to specific acids. A professional jeweller can verify using touch tests.
The Easiest Way: Get Professional Assessment
If you're uncertain about any piece, bring it to a professional.
What Pura offers:
- Free initial visual assessment
- Hallmark verification
- Magnet and specific gravity testing if needed
- XRF analysis for metals (paid service, around R200–R400)
- Certification referrals for diamonds and gemstones
- Professional opinions on authenticity
No obligation, no pressure.
Frequently Asked Questions
Q: Can I test gold at home?
A: Yes, with the magnetic test, weight comparison, and specific gravity test. For definitive results, professional XRF or acid testing is more reliable.
Q: Is white gold the same as platinum?
A: No. White gold is gold mixed with other metals and then rhodium-plated to look white. Platinum is a different, rarer metal. They feel different, cost differently, and require different care.
Q: How do I know if a diamond is lab-grown or mined?
A: Lab-grown and mined diamonds are chemically identical. Only a professional gemologist using specialized equipment can tell the difference. The difference should be disclosed by the seller.
Q: Are moissanites fake diamonds?
A: They're not diamonds, but they're not fake—they're a different gemstone. Moissanite is beautiful, durable, and less expensive than diamond. But it should be sold as moissanite, not as diamond.
Q: What's the difference between treated and synthetic gemstones?
A: Treated gemstones are natural stones that have been enhanced (heated, irradiated, etc.). Synthetic gemstones are created in labs and aren't naturally occurring. Both should be disclosed.
Q: Can I get a diamond tested for free?
A: Many jewellers offer free assessment, but comprehensive testing (XRF, gemological report) typically has a fee. At Pura, basic assessment is free; advanced testing is paid.
Q: Is a hallmark proof that jewellery is real?
A: Hallmarks are a strong indicator, but not foolproof. Counterfeits can be hallmarked. Combined with other tests (weight, magnet test, professional assessment), hallmarks are reliable.
Q: What if I find old jewellery without hallmarks?
A: Bring it to a professional. Old pieces sometimes lack clear hallmarks due to age or wear. A jeweller can assess it and often determine purity through testing.
Trust but Verify
Authenticity matters because it affects value, durability, and the meaning of the piece.
If you're buying new, buy from reputable sources and request documentation.
If you're buying pre-owned or inherited, get professional assessment.
If you're uncertain, ask questions. A legitimate seller or jeweller will be transparent.
At Pura, we're happy to help you verify any piece. No matter where it came from, we can tell you what it really is.