The Anti-Tutorial…Opals

So, browsing around Pinterest the other day, and I saw a pin saying "Polymer Clay Opal Technique". Being  me, and loving opals way too much (seriously, my etsy wishlist is full of them) I clicked.
I was horribly disappointed. They looked nothing like opals.*
For the record, here's a few options for opals from around the world. 
Black Opal
White Opal
Boulder Opal
 
Mexican Fire Opal
Sadly nothing I could find looked even remotely like that. I wept! There are no opal tutorials. D: What's a gem loving girl to do? 
And then......
I found this.
Those two examples, look amazing! I especially love the one on the right. 
I couldn't find anything close to those though. :( No one else seems to have figured out their technique.
But I came close with this lovely one.
The bottom one gives me some ideas... although it would mean that I'd have to get liquid polymer clay and sparkly bits somehow... 
* I'm not going to link directly to any of these, because, well, that would be mean. 
What are your thoughts on faux opal techniques? Do you have anything to share? Comment below!