a. A hard, spherical aggregate of many very small diamond crystals,
usually cryptocrystalline, arranged radially and more or less
concentrically around a central point. Because of their structure, ballas
are classed as industrials that are occasionally used in diamond-drill
bits and other diamond tools. See also: shot bort
b. A dense, globular aggregate of minute diamond crystals, having a
confused radial or granular structure lacking through-going cleavage
planes, giving it a toughness that makes it useful as an "industrial
diamond". CF: bort; carbonado.
c. A term incorrectly applied to a rounded, single crystal of diamond.
d. See: balas ruby
Dictionary of Mining, Mineral, and Related Terms