Welcome to opalholicsanonymous.com where opal season lasts forever.

the opal is stunning but I've seen this type of pattern not only in Welo but in Oz opals ..and in my opinion both Welo and Oz opals form same or similar type of 'tubes' -- which can form different patterns depends on the rough and cutting orientation -- which mean you need to cut it 'right way' -- also not always the 'tubes' have regular shape and they can be 'invisible'
*to me this type of pattern is how real - ribbon mackerel pattern - is and should look like

Wow

What a ripper! I could get lost in that one.

here new video from BOD with interesting info about mining the Rainbow Serpent ... & some more opals