These Boulder Opal Specimans Exibit small amounts of precious opal in its host rock ,however think if they where full faced their value would be in the thousands. Here is some Opal Pattern descriptions .

Harlequin - this Rare pattern features large angler patches of colour closely set together resembling a chequered board.

Pinfire - Characterised by small closely spaced patches or specs of colour with pinpoints that turn on & off resembling sparks..

Flash -large area's of colour that change dramatically with different angles of light creating a stunning visual effect.

Ribbon - Lines of Colour that follow the contours of the Opal often creating a layered appearance.
These patterns combined with the vibrant play of colour with its optical Phenomenon s and natural shapes inherent to Boulder Opal is why they are sought after by collectors and Jewellery enthusiasts alike