1000 Old Pesos Sor Juana (1991): Value & Worth

If you inherited or found a Mexican 1000 Pesos coin dated 1991 with Sor Juana Inés de la Cruz on it, here is the honest answer up front: in circulated condition it is worth a few US cents to about 1 USD. This is a common circulation coin, not a rarity. Only pristine, uncirculated examples pull a small premium, and even those top out at a few dollars.

The number 1000 confuses a lot of people. This is an old peso coin from before Mexico's 1993 currency reform, when the country dropped three zeros. So 1000 old pesos became 1 new peso. It is no longer legal tender and cannot be spent or exchanged at a bank. Its value today is purely collectible.

What this coin actually is

Sor Juana Inés de la Cruz was a 17th-century Mexican poet and scholar, and her portrait appears on the reverse of this coin. It was struck at the Casa de Moneda de México (the Mexican Mint), marked with the small "Mo" mint mark. It belongs to the pre-1992 modern peso era.

Specifications (verify yours against these):

Obverse: The Mexican coat of arms (an eagle on a cactus devouring a snake) with the inscription "ESTADOS UNIDOS MEXICANOS."

Reverse: The portrait of Sor Juana Inés de la Cruz with the face value "$1000," the year "1991," and the "Mo" mint mark.

What it's worth in 2026

Be realistic. This coin was produced for everyday circulation and survives in large numbers, so scarcity is not on your side. The metal is aluminum-bronze, which carries no meaningful bullion value (there is no silver or gold here, so no melt floor to protect the price).

The coin gains value in two situations only: it is in genuine uncirculated condition with full luster and sharp detail, or it comes sealed in an original Banco de México presentation package. Everyday worn examples from a coin jar are common and inexpensive. Check the grading and condition guide to place your piece.

Is it silver? No

A lot of people ask this because the coin has a bright, brassy tone. It is not silver and not gold. It is aluminum-bronze, an alloy used for low-denomination circulation coins. If you are looking for Mexican silver, that is a different category (see our guides on the Onza Libertad silver bullion coin and older silver pesos).

How to check what yours is worth

1. Weigh and measure it. Use a jewelry scale and a caliper. A genuine coin weighs 0.76 grams and measures 17.04 mm across. Wrong weight or diameter is a red flag.
2. Grade the wear. Look at the high points of the coat of arms and Sor Juana's portrait. Sharp, unworn detail with original shine means uncirculated. Smooth, flat, or scratched surfaces mean circulated.
3. Check for original packaging. A sealed Banco de México blister or presentation set is worth more than a loose coin.
4. Consider certification only if it grades high. Sending a common coin to NGC or PCGS costs more than the coin is worth unless it is a genuine top-grade example.

About "error" coins

Mint errors (off-center strikes, die rotation, double strikes) can multiply value when they are genuine and verifiable. Most "errors" people spot on social media are post-mint damage: dings, corrosion, or wear, not factory mistakes. If you think you have a real error, post clear photos on the Pesoteca forum and let the community weigh in before you get your hopes up.

Have a 1991 Sor Juana coin sitting in a drawer? Post front and back photos in the Pesoteca buy-and-sell forum and we'll help you figure out if it's a common example or something worth grading.

The circulating Mexican peso coins of the second half of the 20th century were struck in alloys that changed according to the cost of metals and inflationary processes: .720 silver in the $1, $5, $10, $25 denominations during the 1940s-50s; cupronickel from the 1970s on; aluminum bronze and stainless steel in the 1980s; pieces with historical figures (Hidalgo, Cuauhtémoc, Juárez, Madero, Carranza, Sor Juana) in the late 1980s just before the transition to Nuevos Pesos in 1992. 1991 corresponds to the period when this variant was in circulation. Sor Juana Inés de la Cruz, a New Spain poet, appears on the circulating $1000 denomination of the 1980s, the first Mexican woman to appear on current coinage.