En resumen

A plain-English glossary of 100+ Mexican and world numismatic terms, from proof and BU to macuquina and mule, so you know exactly what you own before you buy or sell.

If you inherited Mexican coins, the biggest obstacle isn't finding a buyer. It's not knowing the vocabulary well enough to describe what you have. Say "old silver coin" and you get lowballed. Say "1947 Cinco Pesos, VF, .900 silver" and the conversation changes. This glossary gives you 100+ numismatic terms in plain English, with the Spanish terms explained, so you know exactly what you own and what to ask for.

Every term includes a short definition, real context, and a Mexican example when it applies. Where dealers misuse a word to inflate a price, we flag it. Learning this list does two things: it keeps you from overpaying, and it lets you talk to any dealer, at auction or online, as an equal.

Section 1. Anatomy of a coin

Obverse (Anverso)

The main face of the coin, the one carrying the coat of arms or the ruler's portrait.

In Mexico the official obverse is the National Coat of Arms (the eagle with the snake). In practice, buyers hunt by the commemorative portrait, not the eagle. On the Onza Libertad 2006 or the 5 Pesos Cuauhtémoc 1947-1948, the primary image is the portrait even though the official obverse is the eagle.

Watch out: if a seller says "the obverse is flawless" while pointing at the portrait, double-check everything else they tell you.

Reverse (Reverso)

The other face of the coin, opposite the obverse.

On modern commemoratives it carries the narrative design. On colonial coins it held the Spanish shield or the pillars. The 8 Reales Columnario Felipe V shows the pillars on the reverse that give the type its name.

Edge (Canto)

The thin rim of the coin, the part that separates the two faces.

Edges come plain, reeded, lettered, or combined. Lettered edges were introduced to stop illegal filing of precious metal. Centenarios carry "INDEPENDENCIA Y LIBERTAD" on the edge.

Watch out: a Centenario with a plain edge or no lettering, walk away. It's either fake or it's been filed.

Field (Campo)

The flat background of the coin, with no relief.

This is where grade gets judged. Scratches or cleaning lines in the field lower the grade. On a proof the field should look mirror-like; on BU it should keep its original mint luster.

Relief (Relieve)

The raised part of the design, what stands up from the field. High relief is more fragile. Always check the high points, that's where wear shows first.

Exergue (Exergo)

The lower section of the design where the date or mint mark sits. On the 8 Reales Resplandor Guadalajara 1879 the exergue carries the date, the "Ga" mint mark, and the assayer's initials. A key zone for cataloging colonial and 19th-century pieces.

Legend (Leyenda)

The text engraved on the coin, usually around the rim. It changes by era: viceregal ("PHILIP V D G HISPAN ET IND REX"), imperial ("AGUSTINUS I DEI PROVIDENTIA"), republic ("REPÚBLICA MEXICANA"), modern ("ESTADOS UNIDOS MEXICANOS").

Denticles (Gráfila)

The ring of beads or teeth next to the rim. Worn denticles indicate a heavily circulated coin. Some colonial pieces had double or triple denticles.

Planchet (Cospel)

The blank metal disc before it receives the struck design. Also called a flan. It's cut from sheet metal, annealed, and run through the die. A defective planchet produces a collectible error coin.

Patina / Toning (Pátina)

The natural layer of oxides and sulfides a coin develops over time.

Blue-gray, charcoal, honey, or rainbow tones on silver; brown or green on copper. It's natural protection against corrosion. Removing it destroys value. See how to care for collectible coins.

Watch out: "I'll clean off the grime so it looks better" almost always means the coin will be cleaned and lose value. An honest seller respects the patina.

Master die / Hub (Matriz)

The original mold carrying the design in negative, from which working dies are derived. It's made once, and several working dies come from it. Subtle changes to the master between years create collectible varieties.

Die (Troquel)

The hardened metal piece with the negative design that strikes the planchet. It produces thousands of coins before wearing out. The first strikes give sharp pieces; the last ones show weak relief.

Section 2. Types of Mexican coin

Cob (Macuquina)

An irregular coin struck by hammer in New Spain between 1536 and 1732, cut from a silver bar rather than a round planchet.

It's the first coin struck in the Americas. Pentagonal, square, or crooked shape; the design rarely comes out complete. There's a modern official recreation in the 100 Pesos Herencia Numismática II Macuquina 2012.

Watch out: fake cobs circulate by the thousands. Without an appraisal or an NGC/PCGS slab, any "cheap" cob is suspect by default.

Pillar Dollar (Columnario)

A colonial coin struck in Mexico between 1732 and 1773 with the reverse showing the Pillars of Hercules crossing the sea.

It's the first round Mexican coin, made with a mechanical press. The reverse shows two crowned pillars over the globe with the motto "PLUS ULTRA." Example: 8 Reales Columnario Fernando VI 1754-1760 Mo-MM.

Bust type (Busto)

A colonial Mexican coin (1772-1821) with the Spanish monarch's portrait on the obverse, replacing the pillar type.

Mexican busts of Carlos III, Carlos IV, and Fernando VII. A modern commemorative version is the 100 Pesos Herencia Numismática Busto 2011.

Cap and Rays (Resplandor)

A republican Mexican coin (1823-1897) with the radiant Phrygian cap design on the reverse.

The iconic design of the first republic. Examples: 8 Reales Resplandor Chihuahua 1889, 8 Reales Resplandor Oaxaca 1879.

Early Eagle (Octaval)

An early republican coin (1823-1830) with eagle and Phrygian cap, forerunner of the full Cap and Rays. First official strikes of the Mexican Republic. Example: 8 Escudos Octaval 1831 México.

Decimal coinage (Decimal)

A Mexican coin under the decimal system (peso divided into 100 centavos), in force since 1863. It replaced the colonial system where a real was one-eighth of a peso. Before 1863 people thought in reales; after, in centavos.

Bimetallic (Bimetálica)

A coin with an outer ring of one metal and a central core of another.

In Mexico nearly all modern circulating 1, 2, 5, 10, and 20 peso coins are bimetallic, with an aluminum-bronze ring and cupronickel core. See the 20 peso commemoratives and the 2026 World Cup coins.

Silver Kilo (Kilo plata)

A 100 peso coin containing 1 kilogram of pure .999 silver, an investment format from Banxico (Mexico's central bank).

110 mm across, 1,000 grams. Priced by silver weight plus a collectible premium. Examples: 100 Pesos 1 Kilogramo Plata 2008, 1 Kilo 2017 Matte Banxico.

Quarter Real (Cuartillo)

A fractional coin of 1/4 real, the smallest unit of the Spanish colonial system. Small pieces, heavily circulated, hard to find in high grade. Used in everyday 19th-century small commerce.

Trial piece (Prueba)

A piece struck as a technical sample before an issue is approved, in very small numbers with a special finish.

In Spanish, "prueba" has two meanings: the technical trial strike (extremely rare, held in reserve) and the commercial proof (mirror finish sold to the public). They are not the same thing.

Watch out: "it's a prueba" from a seller can mean three different things. Get clarity before you pay.

Proof

A premium finish with mirror fields and frosted relief, struck with polished dies and multiple blows.

Distributed in official Banxico cases. The Proof Onzas Libertad carry "Proof" in the catalog and sell at a premium over the regular version.

Satin

A finish between proof and BU, with a soft satin surface, no mirror shine or full commercial luster. Banxico has issued satin versions of premium pieces in small mintages (silver kilos, for example). They trade above BU due to rarity.

Matte

A finish with no shine, a surface that absorbs light, produced by chemical or mechanical treatment of the dies. Examples: 100 Pesos Herencia Numismática Busto Matte 2011, 1 Kilo Plata Matte Banxico. It looks dull, but that's intentional, not wear.

BU (Brilliant Uncirculated)

A coin that never circulated, with original mint luster. In Mexico it's also called "flor de cuño." It corresponds to MS-60 through MS-63 on the Sheldon scale. It's the default for freshly issued circulating commemoratives.

UNC (Uncirculated)

A general synonym for an uncirculated coin, used as an informal shorthand. In the Mexican market "UNC" gets applied to everything: truly uncirculated pieces (correct), almost uncirculated (acceptable), and circulated but cleaned (where the deception starts). See grading condition.

Section 3. Mint and assayer

Mint (Ceca)

The facility that officially strikes coins under state authority.

The Mexico City mint operated from 1535, the first in the Americas. In the 19th century, provincial mints opened in Zacatecas, Guanajuato, San Luis Potosí, Culiacán, Guadalajara, Durango, Oaxaca, Chihuahua, Álamos, and the State of Mexico. The Casa de Moneda de México is the only one active today.

Assayer (Ensayador)

The official who verified the metal's fineness before striking, whose initial was engraved as a signature. Colonial and 19th-century republican coins show two assayer letters next to the mint mark. "Mo-MM" means the Mexico City mint with assayer Manuel Malanco Marquiña.

Engraver (Grabador)

The artist responsible for the design who carves the master die. In New Spain, famous engravers signed with initials near the bust or edge. The modern Casa de Moneda designs the commemorative series (States, Bicentennial, 2026 World Cup).

Mint mark (Marca de ceca)

The initial or initials identifying the facility that struck the coin. Mexican marks: Mo (Mexico City), Zs (Zacatecas), Go (Guanajuato), Ho (Hermosillo/Álamos), Ga (Guadalajara), Do (Durango), Oa (Oaxaca), CH or CN (Chihuahua/Culiacán), Pi (San Luis Potosí), C or CE (Real del Catorce), EoMo (State of Mexico). Modern coins carry only Mo.

Catalog reference (Referencia catalográfica)

A code that identifies a piece in a standard catalog without ambiguity. The most used in Mexico: Krause (KM), Numista (N#), the Banxico Numismatic Collection, PCGS CoinFacts, the NGC World Coin Price Guide, and PSM (Pesoteca Sistema Mexicano).

KM number (KM#)

The identifying number in the Krause "Standard Catalog of World Coins." The Centenario 50 pesos gold 1921 is KM#481. Serious collectors quote by KM# because it removes ambiguity. Krause is updated every year.

PSM ID

The unique identifier in the Pesoteca Sistema Mexicano catalog for each distinct physical piece. Each finish (satin, proof, matte) has its own PSM ID even when it shares a design. It's the site's internal reference.

Banxico inventory ID

The official inventory code Banxico assigns to each piece in its Numismatic Collection. It appears in the Banxico Numismatic Collection, open to the public since 2026.

Krause vs Numista vs Banxico

The three most consulted systems among Mexican collectors. Krause is the traditional US catalog. Numista is the French community wiki (free). Banxico is the official Mexican source. The PSM system adds granularity by finish. When they disagree on Mexican pieces, Banxico wins.

Engraver's signature (Firma del grabador)

The designer's initials hidden on the coin as a mark of authorship. The modern Casa de Moneda doesn't always publish who engraved a piece. On the 1 Onza Libertad Plata 2006 they appear discreetly on the reverse, traceable with a loupe.

Section 4. Grades of preservation

Sheldon scale (Escala Sheldon)

A grading system from 1 (Poor) to 70 (perfect), created by Sheldon in 1949 and adopted as the standard by NGC and PCGS.

In Mexico almost nobody speaks in pure Sheldon numbers, but the letter abbreviations are used: PO, FR, AG, G, VG, F, VF, EF, AU, MS. See the complete grading guide.

PO (Poor)

Grade 1 Sheldon. A coin barely identifiable. Only collectible on extremely rare pieces (cobs, insurgent coins) when nothing better exists.

FR (Fair)

Grade 2 Sheldon. Details heavily eroded but identifiable. Applies only to rare historical pieces after centuries of hard circulation.

AG (About Good)

Grade 3 Sheldon. Outlines visible, legends nearly illegible. Collectible on rare old pieces. A cob in AG has value from absolute rarity.

G (Good, G-4 and G-6)

Grade 4-6 Sheldon. Full design with general wear, legends legible but faint. On colonial Mexican coins, G is the most common grade because they circulated for 300 years.

VG (Very Good, VG-8 and VG-10)

Grade 8-10 Sheldon. Moderate wear, main details visible. VG is the "normal collectible" floor for 19th-century pieces.

F (Fine, F-12 and F-15)

Grade 12-15 Sheldon. Clear design with wear on the high points. Saying "it's F" signals a seller who knows the vocabulary. F is common among circulated high-value Mexican coins.

VF (Very Fine, VF-20 to VF-35)

Grade 20-35 Sheldon. Light wear, most fine details preserved. A VF from the Porfirio Díaz era is already respectable. This is what most people call "well preserved."

EF or XF (Extremely Fine, EF-40 and EF-45)

Grade 40-45 Sheldon. Slight wear on the highest points, the rest almost perfect. An EF 1947 Cuauhtémoc peso starts to be worth several times its silver value. This is where grade begins to outweigh metal.

AU (About Uncirculated, AU-50 to AU-58)

Grade 50-58 Sheldon. Almost uncirculated, tiny wear on the highest points. See the complete guide to tell AU-58 from MS-60.

MS-60 to MS-70 (Mint State)

Grades 60-70 Sheldon. Truly uncirculated, separated by bag marks, luster, and strike quality. MS-65 is Gem UNC. MS-70 is perfect, nearly impossible on old coins. On modern Proof Onzas Libertad, MS-70/PF-70 does happen.

Cleaned

An NGC/PCGS label for coins showing evidence of cleaning (polishing, chemicals, scrubbing).

It cuts value by 30% to 70%. It's irreversible. See how to care for collectible coins.

Watch out: "it's polished so it looks better" means "it's cleaned and no longer worth the same."

Altered (Altered Surface)

A surface modified chemically (silver plating, artificial toning, lacquer). Worse than cleaned. It can lose up to 80% of value. NGC/PCGS mark it as "Details, altered surfaces."

Damaged

Physical damage: dents, deep scratches, holes, solder, engraved initials. It drops value severely but not completely. A rare piece is still collectible when damaged if it's the only one available.

Environmental Damage

Damage from exposure to corrosive conditions: humidity, acids, reactive metals. Different from cleaned because it's involuntary, from poor storage. It shows up on coins from rusty boxes, old PVC albums, or rain exposure.

PVC Damage

Environmental damage specifically caused by polyvinyl chloride flips or albums. Green sticky spots or a yellowish film. Preventable by switching to polypropylene or Mylar holders. See how to care for collectible coins.

Section 5. Metal composition

Silver .720

An alloy of 72% silver, the "low silver" of mid-20th-century Mexico. The Cuauhtémoc peso 1947-1948 and some Morelos pesos are .720. Value is based on pure silver weight, not total weight.

Silver .900

A 90% alloy, the "standard silver" of the 19th century. Porfirian pesos ("thick neck" and "thin neck" varieties) plus the 8 reales Cap and Rays are .900.

Silver .925 (Sterling)

A 92.5% alloy, known as sterling, common in modern commemoratives. Pieces like the 20 pesos Bicentennial are .925.

Silver .999 (Pure silver)

99.9% silver, the world standard for bullion coins. Modern Onzas Libertad are .999.

Silver fineness (Ley de plata)

The proportion of pure silver in the alloy, in thousandths (.720 = 720 parts per thousand). "What's the fineness?" is the mandatory question before pricing by weight.

Gold fineness (Ley de oro)

The proportion of pure gold in the alloy, in thousandths or karats. Centenarios (50 pesos gold) are .900 (37.5 g of pure gold in a 41.67 g coin). See the Centenario guide.

Cupronickel (Cuproníquel)

A copper-nickel alloy used in modern fractional coins and in bimetallic cores. Modern circulating commemoratives use a cupronickel core in several denominations.

Aluminum-bronze (Bronce aluminio)

A copper-aluminum alloy for the outer ring of modern bimetallic coins. It's the "golden" ring of the 20 Pesos Cuauhtémoc aluminum-bronze 1988 and nearly all 21st-century circulating bimetallics.

Stainless steel (Acero inoxidable)

An iron-chromium-nickel alloy used in some modern fractional coins to cut cost. Durable but less distinctive, used as a coating in recent issues.

Bimetallic (composition)

A piece with an outer ring of one metal and a core of another, bonded during striking. All modern 20 peso commemoratives are bimetallic: aluminum-bronze ring with cupronickel core.

Section 6. Issues and variants

Mintage (Tiraje)

The total number of pieces struck for an issue. Banxico publishes it in its official Numismatic Collection. Low mintage raises the price only when demand exists; rare without demand isn't worth more, it's just rare.

Limited edition (Edición limitada)

An issue with a fixed low mintage that can't be expanded, usually with a premium finish. Banxico announces these in the official gazette with a maximum mintage. Example: 1 Kilogramo Plata 2008.

First Strike (Primera acuñación)

Pieces from the first blows of a new die, with maximum relief. NGC/PCGS flag these as "First Strike" or "Early Release."

Watch out: "first strike" without official certification is just words. Without a slab labeled First Strike, don't pay a premium.

Restrike (Reacuñación)

A later issue of an original piece, same image but different date. The classic case: Centenario restrikes. Originals are 1921-1925; restrikes from 1943-1972 carry the "1947" date even when produced in other years. Worth less than an original but the same gold weight.

Token (Ficha)

A struck piece that circulated as a substitute for official coinage in a private, mining, or commercial setting. Porfirian hacienda tokens, mining tokens from Sonora and Zacatecas, 19th-century shop tokens in areas without official coinage. Collectible for regional history.

Emergency coinage (Moneda de necesidad)

A piece issued during crisis or conflict by local authorities without federal authorization. Revolutionary "cartones" (1913-1917) and pieces from independence-era provincial juntas are examples.

Insurgent coin (Moneda insurgente)

An unofficial issue during the War of Independence (1810-1821) by insurgent forces. Examples: 8 Reales Insurgente 1811, 1812, 1813. Extremely rare pieces with abundant counterfeits.

Colonial coin (Moneda colonial)

A piece struck in New Spain (1535-1821) under Spanish imperial authority. Includes cobs, pillar dollars, bust types, and transitions. The oldest segment of Mexican numismatics.

Pattern (Patrón)

An official trial piece from the mint as a technical sample, in one or two units. Unique pieces held at Banxico or in specialized collections. International auction pricing.

Unique piece (Pieza única)

A piece of which only one known example exists. Object of record-setting auctions. Different from "very rare": unique means one; very rare can mean two or three.

Die twin (Gemela)

Nearly identical pieces of the same year with a subtle difference (letter, pointer, digit). They require a specialized catalog. The difference can multiply the price.

Die pairing

A specific combination of dies used in a striking, identified by advanced catalogs. A single year can have several die pairings, some rarer than others.

Repunched (Sobrepunzonado)

A variety where a letter or digit was punched over a previous one in the die. Common in 19th-century Mexico from reusing dies to save cost. A typical date reads "18/17" (1818 over 1817). Collectible.

Section 7. Finishes and variants

Regular (BU/Circulating)

The standard finish meant for circulation or basic collecting, with no premium treatment. 95% of what circulates. Circulating commemoratives reach the public through change, banks, or Banxico.

Proof (finish)

A premium finish with mirror fields and frosted relief, polished dies and a double strike. Distributed in official cases. Example: 1/20 Onza Libertad Plata 2008 Proof.

Matte (finish)

A finish with no shine and an absorbing surface, from chemical or mechanical treatment. Example: 100 Pesos Herencia Numismática Busto Matte 2011.

Satin (finish)

A finish between proof and regular, with a soft satin surface. Satin issues come in limited mintages with a collectible premium. They appear on silver kilos and some commemoratives.

Uncirculated

A generic description of a coin that hasn't circulated, unhandled. Same as BU in North American usage. In Mexico it's used as a synonym, though technically it covers MS-60 through MS-70.

Circulated (Circulada)

A coin that circulated and shows wear, below AU on the Sheldon scale. "Circulated" is honest; "lightly circulated" is acceptable when it's a real AU/EF; "nice circulated" is language to hide wear.

Antique (Antigua)

A generic term for an old coin, with no precise technical meaning. Serious collectors avoid "antique" alone because it says nothing. They prefer to date it: colonial, 19th century, first republic, Porfirian, revolutionary.

Vintage

A borrowed English term for 20th-century coins from before 1980. On online marketplaces it's used to inflate perceived value. Vintage is not an official category, it's a marketing adjective.

Encapsulated (Encapsulada)

A piece sealed in an acrylic capsule (Air-Tite, Guardhouse) or a certification slab (NGC, PCGS, ANACS). From a grading service it's proof of authenticity and grade. From the owner in an Air-Tite it's only physical protection.

Sealed (Banxico blister)

A piece in its original Banxico or Casa de Moneda packaging, unopened. Many of the 2026 World Cup commemoratives carry a premium in sealed blister packs. An intact Banxico seal adds value.

Section 8. Errors and varieties

Doubled die (Doble troquel)

A variety with a duplicated design from a second, shifted impression of the die on the same planchet. Letters or features duplicated, visible to the naked eye. See Mexican minting errors. When cataloged, it multiplies value.

Missing edge (Moneda sin canto)

A piece struck without a reeded or lettered edge, with a fully plain rim. An easy-to-spot error on modern circulating coins. Collectible as an error.

Defective planchet (Planchet defectuoso)

A planchet with a flaw before striking (hole, fold, crack, lamination). The coin inherits the defect. Collectible when clearly identifiable.

Off-center

A die that struck the planchet off-position, leaving part of the design and planchet unstruck. Off-center at 5% isn't collectible; 15% or more carries a premium.

Clip planchet

A planchet with a cut on the rim (curved or straight) from an error in the blanking machine. A coin with a "bite" out of the edge. Collectible as an error variety.

Weak strike (Filete débil)

A strike with incomplete rim relief from insufficient die pressure. On normal pieces it's just a quality defect. On rare ones it adds value as a documented variety.

Mule (Moneda mula)

A piece combining the obverse of one denomination with the reverse of another from a die selection error. Rare and sought after. Counterfeits get sold as mules constantly. Walk away without an appraisal.

Date error (Error de fecha)

A variety where the date appears partly wrong from a mis-engraved digit in the die. The famous international case is the US 1955 doubled die. In Mexico it shows up in mid-20th-century issues.

Overstrike (Sobredato)

A strike made over a previous coin with a design, leaving traces of the earlier one visible. In colonial times it was common to restrike old coins to update the design, saving metal. Collectible historical objects.

Overdate

A date struck over a previous one on the same die, to reuse old dies. Overdates like "1818/17" or "1900/898" are collectible pieces documented by catalog.

Section 9. The Mexican market: places and shorthand

You'll run into these terms if you buy or sell inside Mexico, whether in person or through Mexican sellers online.

Reseller / middleman ("Coyote")

A Mexican reseller who buys low and sells high without full disclosure, working in downtown Mexico City, Azcapotzalco, or regional flea markets. See reseller markups in Mexico. An honest seller explains grade, fineness, and mintage; the informal one just says "it's worth a lot, take it."

La Palma (Mexico City coin street)

A street in Mexico City's historic center where numismatic shops and resellers have traditionally operated. The heart of the Mexican physical market. See reputable coin shops in Mexico City.

Azcapotzalco

A northern district of Mexico City with the country's largest weekly coin market. On Saturdays you either find the specific piece you want or walk out with fakes if you don't know what you're doing. Every warning in this glossary applies.

The 1995 crisis (La 1995)

The Mexican peso crisis of December 1994 to January 1995 (the "December mistake") that halved the peso's value. It sent silver and gold prices up. After 1995 many people began stockpiling gold and silver as a hedge, shifting demand toward physical pieces.

"El cabezón" (the 1947-1948 Cuauhtémoc peso)

A nickname for the 5 Pesos Cuauhtémoc 1947-1948, from the oversized head of the emperor. One of the most popular silver pieces in everyday collecting. It's in nearly every inherited Mexican collection. See 5 Pesos Cuauhtémoc 1947-1948.

"Onza" (the silver Libertad ounce)

In the Mexican market this refers specifically to the Banxico silver Onza Libertad. When someone says "I've got some onzas," they mean Onzas Libertad, not a generic ounce. See what an Onza Libertad is worth in 2026.

"A Centenario" (Un centenario)

A reference to the Centenario 50 pesos gold, whether an original 1921-1925 or a later restrike. The standard Mexican gold reference for personal investment. 37.5 g of pure gold. See the 2026 guide and original vs restrikes. Example: Centenario 50 pesos gold 1925.

Watch out: if a seller offers you "a cheap Centenario" without saying whether it's original or restrike, walk away. The difference runs into thousands of dollars.

"Cachito" (a colonial coin fragment)

A fragment of a cob or colonial coin physically cut into quarters or eighths as change in viceregal commerce. Irregular pieces with part of the original design. Collectible as witnesses of colonial trade before there was enough fractional coinage.

Appraisal tray (Charolita)

A velvet or felt tray where coins are placed during a formal appraisal, with no finger contact. Serious appraisers use a tray, cotton gloves, and at least a 10x loupe. If someone sells you an important piece with no tray and no gloves, it isn't a professional appraisal.

Section 10. Appraisal and value

Appraisal (Peritaje)

A technical examination verifying authenticity, fineness, grade, and market value. It involves physical inspection with equipment (loupe, scale, density test, edge check), a signed document, and the seal of a registered appraiser. See certified numismatic appraisers in Mexico.

Formal valuation (Avalúo)

A formal monetary value assigned to a piece with an appraiser's signature for legal, estate, or insurance purposes. More formal than an appraisal, with legal standing. Used for inheritances and insurance on large collections.

Numismatic appraiser (Perito numismático)

A professional certified in verification and valuation, affiliated with a college or an auction house. Mexico has few formally registered ones. See certified numismatic appraisers in Mexico. Be careful with anyone who self-appoints without credentials.

NGC certification

The service of Numismatic Guaranty Corporation (US), an international standard. It seals the piece in a slab with a label for authenticity, Sheldon grade, date, and cataloging. See it applied in how to spot a fake Onza Libertad.

PCGS certification

The service of Professional Coin Grading Service (US), a direct competitor of NGC with an equivalent reputation. PCGS and NGC are the two majors recognized by the Mexican market.

Encapsulation (slab)

Sealing a coin in an airtight acrylic capsule with an authentication label, done by NGC, PCGS, or another grading service. It protects and documents. Without a slab, a piece loses credibility at international auctions.

Slab

The rigid capsule the coin is sealed in after certification, with a printed label. An NGC/PCGS slab with a high grade is a market object in itself. At international auction, the slab outranks the seller's word.

Grade

The numeric or letter rating of a coin's condition, per Sheldon or equivalent. Listings use "grade" in English even in Mexico. "MS-65," "AU-58," "VF-30" are grades. No clear grade, no clear price.

Holder

A synonym for slab, the rigid plastic case that holds a certified coin. "It's in an NGC holder" means the same as "it's in an NGC slab."

Market value (Valor de mercado)

The price at which a piece is actually selling at a given moment, not the asking price. Estimate it from closed auction comparables (Heritage Auctions, Stack's Bowers, Morton), not from online classifieds. See most valuable Mexican coins: the real prices.

Spread

The difference between the buy and sell price of the same piece at a given moment. On Mexican bullion (Onzas, Centenarios) the honest spread is 3-8%. Above 15% is abusive.

Markup (Sobreprecio)

The extra amount a reseller charges over fair price, exploiting a buyer's lack of knowledge. Honest seller: 10-25% margin depending on the piece. Abusive reseller: 50-200%. See where to sell Mexican coins in 2026.

Final tip: the best markup detector is comparing three quotes before you close. The median usually sits near fair price. Walking away from anyone asking 30% above the median is almost always right.

The bottom line

Speaking the correct vocabulary doesn't make you pretentious, it keeps you from being overcharged. Every term here has a history, and many have a context where someone misuses the word to inflate a price. Learning them separates the person who knows from the one just starting out, and gives you the language to ask well and negotiate well.

If your next search turns up a term that isn't here, head to the Pesoteca forum and ask. The community answers with real context and examples from the actual market. And the day you walk up to a counter asking about a "reeded edge" or requesting a "matte finish" with confidence, you'll get treated differently. That difference is worth more than any word list.

These four articles round out the core reference set for the Mexican coin collector:

Each one links to catalog entries. If you're going to collect seriously, read them in any order, but read them.