opal

/ˈoʊpəl/

/ˈʌʊpəl/

Other forms: opals

An opal is a gem, a semi-precious stone that comes in many shimmery, partly translucent colors. If your birthday is in October, an opal is your birthstone.

An opal is a mineral made of silica, and it's found within the cracks and notches of many different kinds of rock. Most of the world's supply of opals comes from Australia. A polished opal that's been set in a ring or necklace is usually several shades or colors — most often blues and greens — with sparkles or shimmers decorating the stone. The word opal comes from the Latin opalus, and its ultimate root is probably the Sanskrit upala, "precious stone."

Definitions of opal

1. noun

   a translucent mineral consisting of hydrated silica of variable color; some varieties are used as gemstones
   types:

   black opal

   a dark colored opal with internal reflections of green or red

   fire opal, girasol

   an opal with flaming orange and yellow and red colors

   harlequin opal

   a reddish opal with small patches of brilliant color

   type of:

   mineral

   solid homogeneous inorganic substances occurring in nature having a definite chemical composition

   opaque gem

   a gemstone that is opaque