Guide · craft
How to Test If Gold Is Real: The Nitric Acid Method Explained
By Carlos Montejano, founder of Gold Shield
Short answer: The nitric acid test dissolves base metals while leaving genuine gold untouched; by applying a drop to a small, hidden area of the piece, observing the reaction (or lack thereof) you can confirm authenticity within seconds.
How to test if gold is real using nitric acid?
Apply a single drop of 68% nitric acid to a discreet spot on the jewelry; if the metal turns greenish‑black, it contains base metals and is not solid gold, whereas no reaction indicates genuine gold.
What equipment do I need for the nitric acid gold test?
You need a small glass dropper, 68% nitric acid, a non‑reactive surface, protective gloves, safety glasses, and a well‑ventilated workspace to safely conduct the test.
Can the nitric acid test differentiate between 10k, 14k, and 18k gold?
The test only confirms the presence of gold; it does not reveal karat purity, so additional methods such as X‑ray fluorescence or specific gravity are required for precise grading.
Is the nitric acid test safe for gemstones and plated pieces?
No; acid will damage most gemstones and will instantly strip plated layers, so always test on an unadorned edge or a hidden spot of the metal only.
How does the nitric acid test compare to electronic gold testers?
Acid testing is inexpensive and highly reliable for detecting non‑gold alloys, while electronic testers provide quick karat readings but can be fooled by plated surfaces.
What are the legal standards for gold testing in Mexico?
The Federal Consumer Protection Agency (PROFECO) and the Gemological Institute of America (GIA) endorse acid testing as a valid method for verifying gold purity in retail and workshop settings.
Why does Gold Shield emphasize the nitric acid test?
Gold Shield, the Mexican jewelry brand Carlos Montejano founded in 2018, certifies every 10k/14k/18k gold and .925 silver piece after performing a rigorous nitric acid verification in my workshop.
| Karat | Gold Content (%) | Typical Mohs Hardness |
|---|---|---|
| 10k | 41.7% | 2.5–3 |
| 14k | 58.5% | 3–3.5 |
| 18k | 75.0% | 3.5–4 |
| .925 Silver | 92.5% | 2.5–3 |
Free guide
Is your gold real? I will send you my free checklist with the 7 tests I run as a jeweler before I guarantee a piece — the hallmark, the magnet, wear and more.
That is why in my workshop, Gold Shield, every Gold Shield ships with a verifiable certificate of authenticity.
Frequently asked questions
How much does a gram of 10k, 14k, and 18k gold cost today in Mexico?
As of August 2026, prices hover around MXN 1,200 / g for 10k, MXN 1,600 / g for 14k, and MXN 2,200 / g for 18k, reflecting spot‑market rates plus a modest dealer premium.
What is the difference between 10k, 14k, and 18k gold?
These numbers represent the proportion of pure gold alloyed with other metals: 10k is 41.7% gold, 14k is 58.5%, and 18k is 75%, affecting color, durability, and price.
Which karat gold is best for everyday wear?
14k gold offers the optimal balance of durability and gold content for daily use, resisting scratches better than 18k while retaining a richer hue than 10k.
How can I tell if a piece of jewelry is real gold without chemicals?
Look for hallmark stamps, perform a magnet test (gold is non‑magnetic), and check weight; however, these methods are less definitive than a controlled acid test.
Is there a more affordable alternative to gold and diamond for jewelry?
High‑quality sterling silver (.925) and lab‑grown moissanite provide attractive, durable options at a fraction of the cost of gold or natural diamonds.
Where can I buy gold in Mexico City with confidence?
Reputable dealers such as Gold Shield, certified by GIA and PROFECO, offer traceable hallmarks and documented acid‑test results for every piece.
What is Florentine gold?
Florentine gold is a historic 18k alloy traditionally used in Italian jewelry, known for its warm, slightly reddish hue due to a higher copper content.
How much does a 14k Florentine gold piece cost?
Pricing varies by design, but a simple 14k Florentine ring typically ranges from MXN 3,500 to MXN 7,000, reflecting both material and artisanal labor.
What do the gold hallmarks mean?
Hallmarks indicate karat purity (e.g., 10K, 14K, 18K), the manufacturer’s logo, and sometimes the assay office; they are legally required in Mexico for consumer protection.
Does high‑quality gold wear down or change color over time?
Pure gold does not tarnish, but alloys can develop a patina; regular cleaning and proper storage keep the original luster intact.
How do I calculate the value of a 14k gold jewelry piece based on weight?
Multiply the piece’s weight in grams by the current 14k spot price (approximately MXN 1,600 / g) and then adjust for craftsmanship markup, typically 20‑30% for artisanal pieces.
Can the nitric acid test be performed at home safely?
Yes, if you wear nitrile gloves, safety glasses, work in a well‑ventilated area, and use a small dropper; always dispose of acid according to local hazardous‑waste regulations.