"Nature's Fireworks" - A Beginner's Guide to OPAL - Part 6/7

In this, the final instalment, we learn what factors are involved when determining the value of an Opal and the meanings behind some of those terms used throughout my 7 part series.

Valuing Opals

When determining the value of an opal, several factors are involved:

Type of opal


Base colour

Fire colour

Colour pattern

Brightness of fire

Background (base) Colour:

Solid precious opal is more valuable than a doublet or triplet, and black opal is more valuable than boulder opal, and so forth. The darker the body colour, the more valuable the gem.

Fire Colour:

The clarity of the opals colour is critical when determining the value of the opal. Opal is graded according to its colour, with red fire being the most rare, followed by green/orange, green/blue, blue, and finally, purple. However, brilliance and clarity of colour, along with proportional pattern are the main decision makers; a brilliant blue/green opal can cost more than a dull red. An opal displaying a bright