1949 Mexican Silver Onza (One Troy Ounce): Value & Prices

If you inherited a large silver Mexican coin with a balance scale on one side and an old screw press on the other, you have a 1949 Onza Troy de Plata Pura, the first modern Mexican silver ounce. Most examples are worth their silver content, roughly 30 USD at current spot, but certified high-grade pieces have sold near 250 USD. Here is what actually drives the number.

What you have

"Onza Troy" is Spanish for "troy ounce." This coin was struck by the Casa de Moneda de México (the Mexican Mint) in 1949 to show off the quality of its silver and its machinery. Numismatic records credit it as the first modern silver bullion coin issued by any government in the world, which predates the American Silver Eagle by decades.

The design is by Manuel Luna Negrete. The front (obverse) shows an old screw-type coining press with the legend CASA DE MONEDA DE MÉXICO, the Mo mint mark, and the year 1949. The back (reverse) shows a balance scale with the legend UNA ONZA TROY = 480 GRANOS DE PLATA PURA, PESO 33.625 GRAMOS LEY 0.925, which translates to "One Troy Ounce = 480 grains of pure silver, weight 33.625 grams, .925 fineness."

The specs (these are your authenticity checklist too)

• Metal: .925 silver (sterling)
• Weight: 33.625 grams
• Diameter: 41 mm
• Edge: reeded
• Pure silver content: about 31.1 grams, which is one troy ounce (480 grains)
• Mintage: 1,000,000 pieces

Note the fineness. This is sterling silver at .925, not the .999 pure that later bullion rounds use. The coin still contains a full troy ounce of pure silver because the mint added extra alloy weight to hit that number.

What it is worth

Because it holds close to one troy ounce of pure silver, its floor is the metal value. At current spot that is roughly 30 to 40 USD in melt. It will never fall below that.

Above melt, condition sets the price. In circulated grades it trades from a small premium over melt up to around the low 100s in USD. Certified in high mint state (MS64 to MS65 on the PCGS scale), examples have sold near 250 USD.

Prices move with the silver market and with grade, so treat these as ranges, not fixed quotes.

Is it rare?

Sort of. The 1949 mintage was one million coins, which is not scarce on its own. What makes it interesting is that Mexico did not strike the Onza again until 1978, a gap of almost 30 years. That makes the 1949 the scarcest date in the entire Onza Troy family. It is still not hard to find: it shows up regularly at auction and on the international bullion market. So do not expect a life-changing payday from an average one. A pristine certified example is where the real premium lives.

How to tell if yours is genuine

Start with a scale and a caliper. A real 1949 Onza weighs 33.625 grams and measures 41 mm. Anything meaningfully off those numbers is a red flag.

• Confirm the obverse shows the screw press, CASA DE MONEDA DE MÉXICO, the Mo mint mark, and 1949.
• Confirm the reverse shows the balance scale and the 480-grains legend.
• Check that the edge is reeded, not smooth.
• Silver is not magnetic. If a magnet sticks, it is fake.

If you have any doubt, a professional silver test or grading by PCGS or NGC is the safe route. Certification also protects value when you sell.

Where to sell it

You have a few honest options:

• Numismatic auction houses (Heritage, and in Mexico, Morton) for higher-grade or certified pieces.
• International bullion dealers such as APMEX or JM Bullion, which treat it partly as a silver round.
• Local coin shops for a quick sale at closer to melt.

If your coin is uncirculated or better, getting it graded by PCGS or NGC first usually raises the price enough to justify the fee. For serious buyers, use the Pesoteca shop directory to compare offers instead of taking the first number.

This is a piece from the modern pre-1992 era of Mexican coinage, and it sits at the head of a long bullion series. If you also have later Onzas, compare them against the family; the 1949 is the one worth checking closely.

Got a 1949 Onza with sharp scale detail and no wear? Post clear photos of both sides on the Pesoteca forum and we will help you estimate the grade before you list it.

The Onza Troy de Plata Pura is the first official Mexican bullion series of the modern era. Originally struck in 1949 with a single mintage of 1,000,000 pieces, the series remained discontinued for nearly three decades until its resumption in 1978 with the denomination KM# M49b. Between 1978 and 1980 three annual issues were struck with minor varieties by year in the position of the scale and typographic spacing. In 1982 this series was discontinued when the .999 pure silver Onza Libertad began, formally authorized by decree of the DOF of July 14, 1982. The Onza Troy was struck in .925 silver (not in .999 like the later Libertad), with a gross weight of 33.625 g containing exactly 1 troy ounce (31.103 g) of pure silver. The nickname "Onza Balanza" or "Balance Scale Onza" in international markets comes from the main motif of the reverse: the traditional scale of commerce. Unique historic issue of 1949, predecessor of the bullion series resumed in 1978. Mintage of 1,000,000.