What is Opal?

13/03/2018 47 0 0


The different colours that can
be seen on an opal stem from
the diffraction of light from very small
silica spheres within the gemstone.
This is the reason the colours change
when opal is looked at from different
directions.Larger and more ordered silica
spheres within the stone  result in a
greater range and intensity of colour.
This colour play and interference of light
is called iridescence. This is diferent from the opalescence seen within moonstones.

Most gemstones are facted or cut to calibrated shapes and sizes.,
however opals are often cut as freeform cabochons. This is done
to maximise the colour play of the individual opal. The irregular
shapes makes each opal unique and promotes creativity in design

Left to Right, Opal pendant  and types of opal cabochon jewellery 


Until the end of the 19th century Czechoslovakia was the
main supplier of Opal, however today the biggest source 
is Australia. 
More than 90% of the world's precious opals
come from Australia, and the rest can be found in other
counties such as Brazil, Mexico Indonesia,
Czech Republic,USA, and Ethiopia


Opal is amorphous and can be found inside cavities
within sedimentary rock, such as sandstone or ironstone.
It can also be found running through igneous
rock as a vein. It is made of hardened silica gel which
contains a water content between 5 and 30%. Opal
also acts as a petrifying agent, replacing organic substances
such as wood, shell, and bone,