6.91 Ct 3D Wood replacement opal Shape_Triangle with stripes coloured pink and

with stripes coloured pink and green

A pretty rainbow boulder opal with a wavy pattern on one side

This beautiful boulder opal features beautiful purple hues and caramel colours

A very pretty pair of oval boulder opals

A lovely 7

6.91 Ct 3D Wood replacement opal Shape_Triangle with stripes coloured pink andA fun 6. 91 Ct wood replacement opal in a modern half circle shape. What is Wood Replacement opal? Opal formation commences when silica dissolves in water. At our Russells opal mine we have found that this silica solution occupies a void most probably left by decaying tree roots or branches. In cases where the silica infiltrates organic material before complete decomposition occurs, the organic molecules are replaced by silica. This remarkable process