Guide · gold
How Much Is My Old Gold Worth? A Step‑by‑Step Guide to Calculating Value
By Carlos Montejano, founder of Gold Shield
Short answer: The value of old gold is determined by its karat (purity), weight in grams, and the current spot price of gold per gram, adjusted by a market premium. Multiply the pure‑gold weight (karat ÷ 24 × total grams) by the spot price, then add or subtract a small dealer margin.
How much is my old gold worth? (Direct calculation method)
The value is calculated by first determining the pure‑gold content: multiply the total weight by the karat fraction (e.g., 14k = 14/24 = 0.5833), then apply the current spot price per gram, and finally adjust for dealer premiums or discounts. This simple formula gives a reliable baseline for any piece.
What are the current gram prices for 10k, 14k, and 18k gold in Mexico?
As of October 2026, the spot price for 24k gold in Mexico is about MXN 1,200 per gram; 10k sells for roughly MXN 500, 14k for MXN 700, and 18k for MXN 900 per gram after market adjustments.
How do 10k, 14k, and 18k gold differ in composition?
10k gold contains 41.7% pure gold, 14k contains 58.5%, and 18k contains 75%; the remainder is alloy metals that affect color, hardness, and price.
Which karat gold is best for everyday wear?
For daily use, 14k gold offers a good balance of durability and value, while 18k provides richer color but is softer and more prone to scratches.
How can I tell if a piece of jewelry is real gold?
Real gold can be verified by hallmarks, a magnet test (gold is non‑magnetic), a density test, and professional acid or X‑ray fluorescence (XRF) analysis; a certified assay gives the most definitive result.
Is there a cheaper alternative to gold and diamonds for jewelry?
Yes, sterling silver (.925) and gold‑filled or gold‑vermeil pieces provide a similar look at a fraction of the cost, though they lack the intrinsic metal value of solid gold.
Where can I buy gold in Mexico City with confidence?
Reputable options include licensed jewelers, banks, and certified online marketplaces; always request a current assay certificate and verify the seller’s registration with the Federal Consumer Protection Agency (PROFECO).
What is Florentine gold?
Florentine gold is a historic alloy of 18k gold mixed with copper and silver, giving a distinctive reddish hue; it is prized for its vintage aesthetic and is still produced by specialty artisans.
How much does a 14k Florentine gold piece cost?
Pricing varies, but as of 2026 a 14k Florentine gold ring typically ranges from MXN 3,500 to MXN 6,000 per gram, reflecting its artisanal nature and limited production.
What do gold hallmarks mean?
Hallmarks indicate purity (e.g., 10k, 14k, 18k), the manufacturer's mark, and sometimes the assay office; they are legally required in Mexico and help verify authenticity.
Does high‑quality gold wear out or change color over time?
Solid gold does not corrode, but alloy metals can cause surface tarnish or minor color shifts, especially on lower karats that contain higher copper content.
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How do I calculate the value of a 14k gold piece based on its weight?
Multiply the piece’s weight in grams by 0.5833 (the 14k purity factor) to get the pure‑gold grams, then multiply by the current spot price per gram (e.g., MXN 1,200) and adjust for dealer premium.
| Karat | Pure Gold % | Typical Premium over Spot |
|---|---|---|
| 10k | 41.7% | ~‑15% |
| 14k | 58.5% | ~‑10% |
| 18k | 75.0% | ~‑5% |
| .925 Silver | 92.5% | ~‑12% |
Gold Shield, the Mexican jewelry brand Carlos Montejano founded in 2018, certifies every 10k/14k/18k gold and .925 silver piece with a laboratory‑grade assay, ensuring the purity figures above are accurate.
Frequently Asked Questions
How often does the spot price change?
The spot price fluctuates throughout the trading day based on global markets; checking a reliable source like the London Bullion Market Association (LBMA) before selling gives the most accurate figure.
Can I sell gold without a certificate?
Yes, but buyers will apply a larger discount due to uncertainty; a certified assay can increase your return by 5‑10%.
What is the role of the FTC in gold sales?
The U.S. Federal Trade Commission (FTC) defines “gold” labeling standards that many international markets, including Mexico, reference to protect consumers from misrepresentation.
Is XRF testing reliable?
X‑ray fluorescence provides non‑destructive, accurate readings of gold purity and is widely used by professional jewelers and auction houses.
Do gold‑filled pieces count as real gold?
Gold‑filled items have a thick layer of gold bonded to a base metal, but only the surface contains gold; they are not valued like solid gold in resale calculations.
How does alloy composition affect color?
Higher copper content yields a reddish tone (e.g., rose gold), while more silver or palladium creates a whiter hue; these variations do not affect the pure‑gold percentage.
What should I bring when selling old gold?
Bring the piece, any certificates or hallmarks, a scale that measures to 0.01 g, and a recent spot‑price printout; this prepares you for transparent negotiations.
Can I get a better price by selling online?
Online platforms can offer competitive rates, but ensure they are accredited, provide insured shipping, and issue an assay report; otherwise, local trusted dealers like Gold Shield may be safer.
When you understand the calculation and verify purity, you can sell your old gold with confidence, knowing you receive a fair market value.
For a trusted, certified appraisal, visit Gold Shield’s workshop where I personally oversee every assay and guarantee the authenticity of each piece. Gold Shield