The Collaborative International Dictionary of English v.0.48:

Emerald \Em"er*ald\, a.
   Of a rich green color, like that of the emerald. "Emerald
   meadows." --Byron.
   [1913 Webster]

   Emerald fish (Zo["o]l.), a fish of the Gulf of Mexico
      (Gobionellus oceanicus), remarkable for the brilliant
      green and blue color of the base of the tongue; -- whence
      the name; -- called also esmeralda.

   Emerald green, a very durable pigment, of a vivid light
      green color, made from the arseniate of copper; green
      bice; Scheele's green; -- also used adjectively; as,
      emerald green crystals.

   Emerald Isle, a name given to Ireland on account of the
      brightness of its verdure.

   Emerald spodumene, or Lithia emerald. (Min.) See
      Hiddenite.

   Emerald nickel. (Min.) See Zaratite.
      [1913 Webster]

U.S. Gazetteer Counties (2000):

Esmeralda -- U.S. County in Nevada
   Population (2000):    971
   Housing Units (2000): 833
   Land area (2000):     3588.500280 sq. miles (9294.172662 sq. km)
   Water area (2000):    0.496159 sq. miles (1.285047 sq. km)
   Total area (2000):    3588.996439 sq. miles (9295.457709 sq. km)
   Located within:       Nevada (NV), FIPS 32
   Location:             37.829985 N, 117.556859 W
   Headwords:
    Esmeralda
    Esmeralda, NV
    Esmeralda County
    Esmeralda County, NV