Cairngorm is a variety of smoky quartz, especially referring to fine crystals of this quartz that were mined in Scotland. Most properly, cairngorm comes from the Cairngorm Mountains of the Scottish highlands, and particularly the mountain of Cairn Gorm (literally, 'Blue cairn') in Banffshire, for which both the range and the gem is named.
Cairngorm is usually a smokey yellow-brown color, although it may also be a grey-brown. When cut and polished, it may have the golden color of amber, the shining darkness of grey spinel, or any of the various shades of smoky topaz (the darker forms of cairngorm may be known as morion). It is closely related to citrine (another form of quartz), although it is generally darker in color. The coloration is due to iron oxide and perhaps titanic acid. There are, of course, any number of places where one can mine smoky quartz; cairngorm's claim to fame is that it is a particularly fine and clear crystal, worthy of being used as a gemstone.
Cairngorm is often used in Scottish jewellery and is seen as a source of some national pride. It frequently appears on kilt pins, the hilts of Skean Dhu, necklaces, brooches, and seals.
Cairngorm may also be known as Cairngorum or Scotch topaz (citrine may also be known as Scotch topaz).