1998 Mexico 100 Pesos Gold Teotihuacán (1 oz .999)

If you inherited or found a 1998 Mexico 100 Pesos gold coin from the Teotihuacán Pre-Columbian series, here is the short answer: it contains a full troy ounce of pure gold, so it is worth at least the current gold spot price, plus a collector premium for the proof finish. In 2026, that gold floor alone puts it in the low thousands of dollars.

This is not a rare error coin worth a hidden fortune. It is a modern bullion-and-collector piece, and its value tracks gold more than rarity. That is good news: it has a hard floor and is easy to sell.

What you actually have

The coin is part of Mexico's Pre-Columbian gold series, specifically the Teotihuacán collection featuring the feathered serpent (serpiente emplumada), the deity Quetzalcóatl carved into the ancient city's temples. It was struck at the Casa de Moneda de México, the Mexican mint that has operated continuously since the 16th century.

Key specs, which you should confirm before buying or selling:

Feature	Detail
Denomination	100 Pesos
Year	1998
Metal	Gold, .999 fine
Weight	31.1 g (1 troy ounce)
Diameter	34.52 mm
Edge	Reeded
Finish	Proof (mirror fields, satin relief)
Catalog	KM# 626

The "100 Pesos" face value is symbolic. This coin was made for collectors, not for spending. Its real value comes from the gold content and the proof presentation.

What it is worth in 2026

Because it holds exactly one troy ounce of pure gold, the coin has a built-in floor equal to the gold spot price on the day you sell. That is the number that matters most here.

• Melt (bullion) value: whatever one troy ounce of gold trades for that day. Check a live gold price and that is your baseline.
• Collector premium: these were struck as proofs in limited quantities for the numismatic market, so a well-preserved example with its original mint packaging and certificate typically sells above melt. The premium is modest compared to the metal value, but it is real.

Top condition matters. A proof coin with scratches, fingerprints, or hairlines in the mirror fields loses the premium and drops back toward melt. A pristine, encapsulated example (graded PF/PR by NGC or PCGS) commands the strongest price. If yours still has the mint capsule, box, and paperwork, keep them: they add value.

The myth: "old Mexican gold coin, must be worth a fortune"

We see this constantly. A modern proof gold coin is valuable because of its gold, not because it is rare or ancient. The 1998 date is recent, and these were made specifically to be sold to collectors, so plenty survive. Do not expect a six-figure auction result. Expect the gold price plus a reasonable premium.

That said, the floor is a genuine strength. Unlike a common circulated peso worth a few dollars, this coin will always be worth its ounce of gold. It is one of the more liquid Mexican gold pieces you can own.

How to check what yours is worth

1. Weigh it and measure it. Use a jewelry scale and calipers. It should weigh 31.1 g and measure 34.52 mm. Wrong weight or diameter is the fastest way to spot a fake.
2. Inspect the finish. A real proof has deep mirror fields and crisp, satin-textured relief. Flat, dull, or grainy surfaces are a red flag.
3. Grade it honestly. Marks, spots, and wear in the fields cut the premium. If the coin looks flawless, professional grading (NGC or PCGS) can pay for itself.
4. Price the metal first. Look up the current gold spot price and multiply by one troy ounce. That is your minimum. Any offer far below that is not serious.

How to tell if it is genuine

Gold is heavy and hard to fake cheaply. Counterfeits usually fail on weight, diameter, or detail: underweight, wrong size, flat relief, or off-color plating. If a magnet reacts to it at all, it is not solid gold. When in doubt, a numismatic dealer or a grading service can authenticate it, and a genuine coin sealed in an NGC or PCGS holder removes the guesswork entirely.

Related reading on Mexican gold and how to sell it safely:

• Verified numismatic shops directory, sorted by city, for in-person appraisal.
• Pesoteca buy-and-sell forum to reach collectors directly.
• Coin grading and condition guide to understand what your grade means for price.

Where to sell it

Because this is a precious-metal coin, sell only where the buyer inspects the piece and confirms its weight in front of you. A verified dealer from the Pesoteca shops directory will appraise it on the spot, and the buy-and-sell forum connects you with collectors who understand the proof premium. Photograph the obverse, reverse, and edge before you list it. Avoid dumping it to the first offer on social media, where lowball buyers hunt for people who do not know they are holding an ounce of gold.

Got one of these in a drawer or an inherited collection? Post clear photos of both sides and the edge on the Pesoteca forum and let collectors tell you what your example is really worth today.