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.
      [1913 Webster]

            From the joints of thy prolific stem
            A swelling knot is raised called a gem. --Denham.
      [1913 Webster]

   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.
      [1913 Webster]

   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.
      [1913 Webster]

   Artificial gem, an imitation of a gem, made of glass
      colored with metallic oxide. Cf. Paste, and Strass.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Gem \Gem\ v. t. [imp. & p. p. Gemmed; p. pr. & vb. n.
   Gemming]
   1. To put forth in the form of buds. "Gemmed their blossoms."
      [R.] --Milton.
      [1913 Webster]

   2. To adorn with gems or precious stones.
      [1913 Webster]

   3. To embellish or adorn, as with gems; as, a foliage gemmed
      with dewdrops.
      [1913 Webster]

            England is . . . gemmed with castles and palaces.
                                                  --W. Irving.
      [1913 Webster]

WordNet (r) 3.0 (2006):

gem
    n 1: art highly prized for its beauty or perfection [syn: gem,
         treasure]
    2: a crystalline rock that can be cut and polished for jewelry;
       "he had the gem set in a ring for his wife"; "she had jewels
       made of all the rarest stones" [syn: gem, gemstone,
       stone]
    3: a person who is as brilliant and precious as a piece of
       jewelry [syn: jewel, gem]
    4: a sweet quick bread baked in a cup-shaped pan [syn: muffin,
       gem]
    5: a precious or semiprecious stone incorporated into a piece of
       jewelry [syn: jewel, gem, precious stone]

Moby Thesaurus II by Grady Ward, 1.0:

125 Moby Thesaurus words for "gem":
   Danish, Danish pastry, English muffin, Parker House roll,
   Yorkshire pudding, acceptable person, anklet, armlet, bagel,
   bangle, bead, beads, bejewel, beribbon, beset, bespangle, bialy,
   bialystoker, bijou, boast, bracelet, breastpin, brooch, bun,
   capital fellow, catch, chain, chaplet, charm, chatelaine, circle,
   clover-leaf roll, coffee cake, coronet, cream, crescent roll,
   croissant, cross bun, crown, crumpet, crystal, diadem, diamond,
   earring, elite, engrave, feather, figure, filigree, find, flag,
   flounce, flower, fob, garland, gem stone, gentleman, godsend,
   good fellow, good lot, good man, good person, good sort,
   good thing, good woman, hard roll, honest man, hot cross bun,
   ideal, illuminate, jewel, kaiser roll, lady, locket, marvel,
   masterpiece, mensch, muffin, necklace, nonpareil, nose ring,
   onion roll, paint, pearl, perfect gentleman, perfect lady,
   persona grata, pick, pin, pinwheel roll, plum, plume, popover,
   precious stone, pride, pride and joy, prince, prize, quintessence,
   real man, rhinestone, ribbon, right sort, ring, roll,
   rough diamond, scone, semiprecious stone, soft roll, spangle,
   stickpin, stone, tiara, tinsel, torque, treasure, trophy,
   trouvaille, wampum, windfall, winner, worthy, wreathe, wristband,
   wristlet



V.E.R.A. -- Virtual Entity of Relevant Acronyms (February 2016):

GEM
       Generalized Executive for realtime Multiprocessor applications
(OS)


V.E.R.A. -- Virtual Entity of Relevant Acronyms (February 2016):

GEM
       Graphics Environment Manager (DR, PC)


The Free On-line Dictionary of Computing (30 December 2018):

GEM

    One of the first commercially available
   GUIs.  Borrowing heavily from the Macintosh WIMP-style
   interface it was available for both the IBM compatible
   market (being packaged with Amstrad's original PC series)
   and more successfully for the Atari ST range.  The PC
   version was produced by Digital Research (more famous for
   DR-DOS, their MS-DOS clone), and was not developed very
   far.  The Atari version, however, continued to be developed
   until the early 1990s and the later versions supported 24-bit
   colour modes, full colour icons and a nice looking sculpted
   3D interface.

   (1997-01-10)


U.S. Gazetteer Counties (2000):

Gem -- U.S. County in Idaho
   Population (2000):    15181
   Housing Units (2000): 5888
   Land area (2000):     562.576688 sq. miles (1457.066871 sq. km)
   Water area (2000):    3.169897 sq. miles (8.209994 sq. km)
   Total area (2000):    565.746585 sq. miles (1465.276865 sq. km)
   Located within:       Idaho (ID), FIPS 16
   Location:             43.969570 N, 116.451291 W
   Headwords:
    Gem
    Gem, ID
    Gem County
    Gem County, ID


U.S. Gazetteer Places (2000):

Gem, KS -- U.S. city in Kansas
   Population (2000):    96
   Housing Units (2000): 47
   Land area (2000):     0.325551 sq. miles (0.843174 sq. km)
   Water area (2000):    0.000000 sq. miles (0.000000 sq. km)
   Total area (2000):    0.325551 sq. miles (0.843174 sq. km)
   FIPS code:            26050
   Located within:       Kansas (KS), FIPS 20
   Location:             39.425730 N, 100.896294 W
   ZIP Codes (1990):     67734
   Note: some ZIP codes may be omitted esp. for suburbs.
   Headwords:
    Gem, KS
    Gem