Opal Types

The base colour of black opals are, as their name suggests, black or very dark grey. However, that doesn’t mean that the stone is totally black. In fact, an opal that is just black is worthless. Precious Black opal consists of a layer of precious opal (i.e. opal that has play-of-colour) on a very dark grey to black potch opal. The gemstone is still entirely opal and has formed naturally as a single solid piece. The dark base makes the colours on the black opal glow and really stand out.

In general black opals are the most valuable of all opals and found almost exclusively from
Lightning Ridge Australia. Some limited production also comes from Mintabie and Allan’s Rise in South Australia. The prices of black opals vary from approximately 100 euros to tens of thousands of euros per carat.

A body tone scale has been developed to grade the black opals. Only opals that have the body tone of N1 to N4 can be called black opals. The body tone is determined by holding the stone face up on the scale and compairing its overall body tone to the shades on the scale.

The body tone, however, is only one factor that influences the value of a black opal.  It must be noted as well that the body tone scale as a valuation tool only applies to black and dark opals. White opals and their body tone should be graded differently. Being on the other end of the scale doesn’t mean white opal is lower quality than black opal.