The Collaborative International Dictionary of English v.0.48:

Gem \Gem\, n. [OE. gemme precious stone, F. gemme, fr. L. gemma
   a precious stone, bud.]
   1. (Bot.) A bud.
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            From the joints of thy prolific stem
            A swelling knot is raised called a gem. --Denham.
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   2. A precious stone of any kind, as the ruby, emerald, topaz,
      sapphire, beryl, spinel, etc., especially when cut and
      polished for ornament; a jewel. --Milton.
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   3. Anything of small size, or expressed within brief limits,
      which is regarded as a gem on account of its beauty or
      value, as a small picture, a verse of poetry, a witty or
      wise saying.
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   Artificial gem, an imitation of a gem, made of glass
      colored with metallic oxide. Cf. Paste, and Strass.
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