sapphire \sap"phire\ ? or ?; 277, n. oe. saphir, f. saphir,
   l. sapphirus, gr. ?, of oriental origin; cf. heb.
   sappimacr.
   1. min. native alumina or aluminium sesquioxide, al2o3;
      corundum; esp., the blue transparent variety of corundum,
      highly prized as a gem.
      1913 webster

            of rubies, sapphires, and of pearl'es white.
                                                  --chaucer.
      1913 webster

   note: sapphire occurs in hexagonal crystals and also in
         granular and massive forms. the name sapphire is
         usually restricted to the blue crystals, while the
         bright red crystals are called oriental rubies see
         under ruby, the amethystine variety oriental
         amethyst see under amethyst, and the dull massive
         varieties corundum a name which is also used as a
         general term to include all varieties. see corundum.
         1913 webster

   2. the color of the gem; bright blue.
      1913 webster

   3. zool. any humming bird of the genus hylocharis, native
      of south america. the throat and breast are usually bright
      blue.
      1913 webster

   star sapphire, or asteriated sapphire min., a kind of
      sapphire which exhibits asterism.
      1913 webster
see also:
al2o3 ruby amethyst corundum hylocharis star sapphire 
asteriated sapphire 

sesquioxide \ses`quiox"ide\, n. sesqui- + oxide. chem.
   an oxide containing three atoms of oxygen with two atoms or
   radicals of some other substance; thus, alumina, al2o3 is
   a sesquioxide.
   1913 webster sesquipedal
see also:
al2o3 

alumina \alu"mina\, n. l. alumen, aluminis. see alum.
   chem.
   one of the earths, consisting of two parts of aluminium and
   three of oxygen, al2o3.
   1913 webster

   note: it is the oxide of the metal aluminium, the base of
         aluminous salts, a constituent of a large part of the
         earthy siliceous minerals, as the feldspars, micas,
         scapolites, etc., and the characterizing ingredient of
         common clay, in which it exists as an impure silicate
         with water, resulting from the decomposition of other
         aluminous minerals. in its natural state, it is the
         mineral corundum.
         1913 webster
see also:
alum al2o3 

corundum \corun"dum\ k-oru^n"du^m, n.; pl. corundums
   k-oru^n"du^mz. also corindon. from hind. kurand
   corundum stone. min.
   the mineral alumina al2o3, as found native in a
   crystalline state. transparent varieties are used as
   gemstones, including sapphire, which is the fine blue
   variety; the oriental ruby, or red sapphire; the oriental
   amethyst, or purple sapphire; and adamantine spar, the
   hair-brown variety. it is the hardest substance found native,
   next to the diamond.
   1913 webster +pjc

   note: the name corundum is sometimes restricted to the
         non-transparent or coarser kinds. emery is a
         dark-colored granular variety, usually admixed with
         magnetic iron ore.
         1913 webster
see also:
corundums al2o3 sapphire oriental ruby oriental amethyst adamantine spar 
emery