Obverse: identify the front

The pictured 1902 Republican design has the facing Mexican eagle with a snake and REPUBLICA MEXICANA legend. This older political legend distinguishes it from the later ESTADOS UNIDOS MEXICANOS series. The country emblem alone does not establish alloy or authenticate a specimen; compare it with the exact reverse and dated type.

Reverse: identify the back

The matching reverse displays the 20 centavo denomination within a half-wreath, with date, mint and assayer attribution. It differs from later Liberty-cap twenty centavos. The pictured 1902 pair illustrates one Mo type only; it is not a photograph of every Cn, Go or Zs issue or an attribution of an unseen overdate.

History and purpose

The KM 405 family belongs to the later Republican 20 centavo series, preceding the 5 g, .800 KM 435 standard beginning in 1905. Those two standards overlap in 1905 and must be identified by design and nominal mass. The reduced-size 3.625 g, .800 KM 436 of 1919 and 3.3333 g, .720 KM 438 are also different standards with different silver amounts. A denomination or calendar date alone cannot select the correct calculator.

How to identify this variant

Match a 20 centavo denomination, the Republican-eagle/half-wreath design and the included 1898–1905 date. Keep the nominal 5.415 g standard separate from 5 g, .800, 3.625 g, .800 and 3.3333 g, .720 issues, bronze twenty centavos, patterns and regional pieces. Wear may reduce measured weight; a photograph, household scale or magnet cannot alone establish precise fineness or authenticity. Preserve complete rims and legends for attribution.

Understanding its metal content

The calculator uses .1572 fine silver troy ounce per matching coin. Three matching pieces contribute 16.245 nominal gross grams and .4716 reference fine silver troy ounce. Gross alloy mass is not pure silver mass, and a troy ounce differs from an avoirdupois ounce. Current dollar melt pricing requires an approved market-price feed; missing prices are not displayed as zero. Collector interest is separate from the metal amount.

Dates, varieties and composition changes

Actual included years are 1898, 1899, 1900, 1901, 1902, 1903, 1904 and 1905. Mint-specific runs differ, as the table shows. Overdates include 1900/800 at Go, Mo and Zs, 1901/0 at Zs and 1902/802 at Cn. The reference’s observed denomination-search row separately lists 1904/3 CnH. Undernumerals do not create extra annual years. Assayer letters also differ by mint and date; retain them rather than treating all pieces as one mint.

Melt value versus collector value

Date, mint, assayer, overdate, die pairing, condition and provenance can affect collector interest independently of silver content. The calculator does not establish grade, rarity or a buying offer. Avoid polishing or cleaning, and preserve certification and any established attribution. A complete photograph of both sides and the mint/date area is more useful than a tightly cropped numeral.

Authenticity and condition

The genuine 1902 pair documents one included Mo design, not an assay or authentication certificate for another coin. Its source has an independent CC 0 photo release, but the pictured date, complete design and margins still require actual visual review. Cast copies, plating, altered dates, patterns and uncertain regional pieces need individual investigation. Supply edge images and measured diameter and mass where possible without inferring missing specifications.

Selling this coin

Separate this historical 20 centavo standard from .800, .720 and bronze 20 centavos before entering quantities. Sort by actual mint and date, preserving suspected overdates for individual review. CashForCoins’ existing photo-appraisal flow can carry the selected coin and quantity into an enquiry. An offer may depend on authenticity, condition and collector demand as well as silver; the educational calculation is not a bid.

Sources and calculation methodology

The designated reference World Silver melt reference supplies 5.415 g/.903/.1572 fine silver troy ounce. Dated KM 405(Cn) and 405.2(Mo) give .9030, while 405.1(Go) and 405.3(Zs) give .9027; all four retain 5.4150 g and .1572 oz. This guide discloses the reference-precision difference rather than inventing a composition change or replacing the designated calculation. The inspected reference type records do not supply diameter or thickness; neither is invented for the pictured 1902 coin. Remaining alloy metals and unlisted finishes are not independently established. Four matching reference dated tables supply the actual annual rows; a separate observed search row supports 1904/3 CnH. The reference valuations, mintages and articles are not republished. The paired 1902 photograph is independently CC 0-released on Commons by the account Inri; its photographer is unspecified.

The actual dated representative photographs and independent reuse permissions were inspected. Complete faces are retained, with WebP conversion and no enlargement, retouching or synthetic reconstruction; joined source images are split with complete rims. These photographs do not assay another specimen. Actual staging rendering and calculator acceptance are separately recorded.

Common questions

References

• NGC designated World Silver Coin Melt Values — designated weight; fineness; reference silver ounces; broader group heading (checked 2026-10-12)
• NGC dated20centavosKM405 Cn — dated identity; weight; fineness; reference ounces; dates from annual rows; design; diameter absence reviewed; mint and overdate notes (checked 2026-10-12)
• NGC dated20centavosKM405.1 Go — dated identity; weight; fineness; reference ounces; dates from annual rows; design; diameter absence reviewed; mint and overdate notes (checked 2026-10-12)
• NGC dated20centavosKM405.2 Mo — dated identity; weight; fineness; reference ounces; dates from annual rows; design; diameter absence reviewed; mint and overdate notes (checked 2026-10-12)
• NGC dated20centavosKM405.3 Zs — dated identity; weight; fineness; reference ounces; dates from annual rows; design; diameter absence reviewed; mint and overdate notes (checked 2026-10-12)
• NGC denomination search observed1904/3CnH — additional dated overdate row and matching5.415gdesign (checked 2026-10-12)
• CC0representative1902pairedphotograph — independent photographicpermission; uploaderInri; photographer unspecified; acquisition and visual review pending (checked 2026-10-12)

Issue-year references

• NGC designated World Silver Coin Melt Values
• NGC dated20centavosKM405 Cn
• NGC dated20centavosKM405.1 Go
• NGC dated20centavosKM405.2 Mo
• NGC dated20centavosKM405.3 Zs
• NGC denomination search observed1904/3CnH
• CC0representative1902pairedphotograph

Content maintained by CashForCoins. Last substantive record update: 2026-10-12. Report a specification or attribution issue through our contact page.

Related coins

Mexican .800 Silver Twenty Centavos — 1919 Reduced Size

Photo credits and rights on the linked coin profile.

Mexico • 80% silver; remaining alloy metals not independently verified

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Mexican .720 Silver Twenty Centavos

Photo credits and rights on the linked coin profile.

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