Real gold does not rust, tarnish heavily, or react with most acids. Those properties let you test it at home with basic tools. Start with the free tests (visual, magnet) and escalate to an acid kit only if you still need confirmation.
The one-sentence answer: A magnet test costs nothing and eliminates obvious fakes, a ceramic streak test is free but leaves a mark, and a home acid test kit (around $15–$30) is the most reliable DIY confirmation of karat grade — but only a professional XRF or fire assay is fully accurate for high-value pieces.
Safety First: Acid Test Precautions
The acid solutions in gold test kits are dilute nitric acid. They can cause chemical burns to skin and eyes, damage clothing, and produce mild fumes.
Before you open the acid bottles:
- Work outdoors or at a window with ventilation.
- Wear nitrile or latex gloves — not cotton.
- Wear safety glasses, not just reading glasses.
- Have clean running water nearby to rinse any spills immediately.
- Keep the bottles tightly capped when not in use and store them away from children.
- Do not test near open flames; nitric acid is oxidizing.
- Neutralize spills with baking soda solution before wiping.
Dispose of used acid and swabs according to your local hazardous waste guidelines — do not pour it down the drain in quantity.
Method 1: Visual Inspection and Stamp Check
Start here — it costs nothing.
- Look for a karat stamp inside the ring band, on a clasp, or on the bail. Common marks: 10K, 14K, 18K, 24K (US), or 417, 585, 750, 999 (European fineness). See how to read jewelry hallmarks.
- Check for discoloration at wear points — the inside of a ring shank, where a bracelet rubs the skin. Gold-plated pieces show a different color underneath where the plating has worn through.
- Look for a “GP,” “GEP,” or “HGE” stamp — these mean gold plated, not solid gold.
A stamp by itself is not proof. Counterfeit stamps exist. Use this as a first filter only.
Method 2: Magnet Test
Gold is diamagnetic — it is repelled by, not attracted to, a magnet. Use a strong rare-earth (neodymium) magnet, not a refrigerator magnet.
What the result means:
- Strongly attracted: contains iron or nickel. Not solid gold.
- Weakly attracted: may have a steel clasp or iron-core construction. Investigate further.
- Not attracted at all: passes this test (does not confirm gold — many non-gold metals are also non-magnetic).
The magnet test catches obvious fakes quickly. White gold alloyed with palladium and most rose gold alloys are also non-magnetic, so a passing magnet test tells you only that the base metal is not iron.
Method 3: Ceramic Streak Test
Drag the piece firmly across an unglazed white ceramic tile or the rough back of a porcelain plate.
| Result | Interpretation |
|---|---|
| Gold streak | Likely real gold (the color of the streak will match the karat — 10K leaves a lighter yellow than 18K) |
| Black streak | Likely pyrite (“fool’s gold”) or base metal |
| No streak | Inconclusive — try more pressure |
The ceramic test works but it can scratch soft jewelry. Skip it on pieces with stones or delicate settings.
Method 4: Acid Test Kit (Most Reliable DIY Method)
Commercial acid test kits (sold by gold refiners and jewelry supply companies) include a black testing stone and vials of nitric acid calibrated to different karat levels.
How to do the test:
- Put on gloves and eye protection.
- Make a streak on the black stone by rubbing the piece firmly — 2–3 cm long. Alternatively, apply one drop of acid directly to a small inconspicuous area of the piece.
- Apply one drop of the karat acid to the streak (start with the lowest karat acid, e.g., 10K).
- Observe for 30 seconds.
Reading the result:
| Reaction | Meaning |
|---|---|
| Streak stays gold-colored | Metal is at least that karat level; try higher karat acid |
| Streak turns green or brown | Metal contains base metals — lower karat than the acid, or not gold |
| Streak dissolves quickly | Not gold, or very low karat |
| Streak remains on higher-karat acid | Confirms karat at that level |
Work through the acid vials from lowest to highest until the streak starts to dissolve. That tells you the karat grade.
Limitation: Acid testing confirms the surface layer. A gold-plated piece can pass the scratch-and-streak test if the plating is thick enough. Test at an edge or a worn spot to expose the base metal, or have a professional use XRF.
Method 5: Float/Density Test
Gold is very dense — 19.3 g/cm³ for pure 24K, approximately 15.2–17.5 g/cm³ for 10K–18K alloys. Most fake metals are far lighter.
How to do it:
- Weigh the piece on a precise kitchen scale (in grams).
- Fill a graduated cylinder or tall glass with enough water to submerge the piece completely. Note the water level.
- Lower the piece into the water on a thin thread (so the thread doesn’t add volume). Note the new water level.
- Calculate the volume displaced (mL = cm³).
- Divide weight by volume to get density.
At $4,134.80/ozt gold (October 7, 2026), confirming density pays off on heavier pieces. Compare your result to the table:
| Karat | Typical density |
|---|---|
| 10K yellow | 11.6–12.0 g/cm³ |
| 14K yellow | 13.1–13.5 g/cm³ |
| 18K yellow | 15.0–15.6 g/cm³ |
| 18K white | 14.7–16.4 g/cm³ |
| 24K | 19.3 g/cm³ |
The density test is accurate only on solid, non-hollow pieces. Hollow chains or rings with solder give misleading results.
Method 6: Skin Discoloration
A rough guide, not a test:
- Real gold of 14K or higher leaves no black or green mark on clean, dry skin.
- Lower karat gold (10K) may leave a faint mark on some skin types due to the higher copper content reacting with sweat.
- Gold-plated pieces over brass often leave a green or black mark quickly.
This test depends too much on skin chemistry to be reliable. Use it only as a secondary clue.
When to Skip DIY and Go to a Professional
Have the piece tested by a jeweler or refiner with an XRF (X-ray fluorescence) analyzer if:
- The piece is worth more than $200 in potential scrap value.
- You cannot find a karat stamp.
- Your acid test gave an unclear result.
- The piece contains stones that might be loose or damaged by acid.
- You suspect the piece is fine enough to be worth more than scrap.
XRF reads the full alloy composition nondestructively in under a minute. Many coin dealers and refinery offices offer it for $5–$20.
Next Steps After Testing
Once you know the karat, weigh the piece in grams and enter the numbers into the scrap gold calculator to see the melt value at today’s spot price. For context on what buyers actually pay, read how much is scrap gold worth and how to sell scrap gold.