5 Pesos Silver Coin 1999 (Second Millennium, Nature Conservation)

If you inherited a 1999 Mexican 5 Pesos coin from the "Segundo Milenio, Conservación de la Naturaleza" (Second Millennium, Nature Conservation) series, here is the honest answer: it is a one-ounce silver proof, so its floor is the silver melt value, roughly USD 30 to USD 35 depending on the spot price the day you sell. A clean, certified example can bring more, but this is not a five-figure rarity. Below is what actually drives the price.

What you actually have

This is a commemorative silver coin struck by Banco de México (Mexico's central bank) in 1999, part of a series marking the turn of the millennium and nature conservation. It was made as a proof: mirror-like fields with frosted, matte raised designs. Proof coins were sold in numismatic sets, not spent as pocket change, so most surviving pieces are in good shape.

The hard specs, which matter for both value and authentication:

• Denomination: 5 pesos
• Year: 1999 (single year of issue, no date varieties)
• Metal: .999 fine silver (nearly pure)
• Weight: 31.1 grams (one troy ounce)
• Diameter: 40 mm
• Edge: reeded (grooved)
• Finish: proof, with a pedestal design on the obverse

Because it holds exactly one troy ounce of pure silver, this coin has a built-in floor: it can never be worth less than the value of its metal.

What it is worth in 2026

Two values are stacked here, and it helps to separate them.

Melt value (the floor). One troy ounce of .999 silver tracks the spot price. In 2026, that puts the metal floor in the USD 30 to USD 35 range. Any dealer will pay somewhere near this even for a damaged coin.

Numismatic value (the premium). As a proof commemorative, a clean example carries a premium over melt. What lifts it above the floor is condition, original packaging, and buyer demand for the series.

Condition	What it means	Approximate value (USD)
Damaged / cleaned	Scratches, spots, wiped surfaces	Melt value, roughly 30 to 35
Proof, no packaging	Nice mirror fields, loose	35 to 55
Proof in original Banxico blister	Sealed or original holder	50 to 80
Certified PF67 or higher (NGC/PCGS)	Graded and slabbed	80 and up, demand-driven

These are working ranges, not fixed quotes. The Mexican proof-silver market is thin, so the price you get depends heavily on finding a collector who wants this exact piece at that moment.

Why it is not a fortune (and that's fine)

A 1999 date feels "old" to a lot of people, but 1999 is recent in numismatic terms, and this coin was made for collectors, not for circulation. It was never rare in the way a low-mintage 19th-century piece is rare. Banco de México did not publish an official mintage for this issue, which usually points to a limited numismatic-set release rather than a mass production, but no confirmed figure exists. Treat any "exact mintage" claim you see in a forum as unverified.

The value story here is simple: it is real silver, in a collectible proof format, worth a modest premium over its metal. That is a solid, liquid thing to own. It is not a lottery ticket.

How to check if yours is genuine

Fakes of Mexican silver do circulate, so verify before you buy or sell.

1. Weigh it. It must be 31.1 grams. A digital jewelry scale settles most cases fast. Off by more than a few tenths of a gram, be suspicious.
2. Measure it. 40 mm diameter. Wrong size is an instant red flag.
3. Ping test. Balanced on a fingertip and tapped gently, real .999 silver rings with a high, sustained tone. Fakes made of base metal sound dull and short.
4. Check the surfaces. A genuine proof has sharp mirror fields and clean frosted relief. Blurry lettering or mushy detail suggests a cast copy.
5. For real money, get it graded. If your coin looks high-end, sending it to NGC or PCGS (the two major grading services) is the definitive answer. A slab confirms authenticity and grade, and it raises resale value.

Where to sell it

Because the value is close to melt, do not overpay for handling, and do not dump it to the first buyer either.

• A verified coin shop gives you an on-the-spot valuation and takes the guesswork out. This is the safest route for a single piece.
• Collector marketplaces and forums can beat dealer buy prices if you are patient and your photos are good.
• General online listings often have the lowest prices but also the most fakes, so if you buy there, always ask the seller for the weight and a photo of the edge.

Whoever you deal with, photograph the obverse, reverse, and edge, confirm the weight, and check the grade ranges above before agreeing to a number. For a full walkthrough on assessing condition, see our coin grading guide, and you can find vetted buyers in the Pesoteca shop directory or trade directly with collectors in the buy-and-sell forum.

Not sure whether yours is a plain proof or a certified-grade piece? Post clear photos in the Pesoteca forum and let the community weigh in before you sell.