Jemmy.
Spruce, fine. A diminutive of gim, spruce or smart (Anglo-Saxon gemet). Gimcrack means an ornamental toy, a pretty ornament of no solidity. (See below, Jemmy Jessamy.)
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Entry taken from Dictionary of Phrase and Fable, edited by the Rev. E. Cobham Brewer, LL.D. and revised in 1895.