5 centimes Essai en nickel de Merley, type I à 20 pans

Merley's multi-sided trial designs for the French centime series were produced internally at the Monnaie de Paris as part of an extended competition to reform small-denomination coinage that dragged on for years without resolution. The type I twenty-panel variant represents one of the earlier geometric experiments, the faceted edge being a proposed anti-counterfeiting measure at a time when struck nickel blanks were relatively easy to fake with base-metal substitutes.

No type based on Merley's twenty-panel design ever reached circulation. GEM 12.4 places this among a sequence of rejected trials, most surviving in tiny quantities distributed to official archives or acquired directly by contemporary collectors through the Monnaie's own sales program.