Boulder opals that have a little blue and green blue flash. And probably myriad other colors(I see a little flash of green and lavender as well Purchased in Tasmania Australia The oval blue gemstone also was purchased in Australia (though I’m not sure it’s actually considered boulder opal and I intended to set it in a ring or pendant but never quite got around to it All purchased circa 2009 Ideal for wire wrapping The backs of the oval cabochons are smoothly finished and ready to be set wire wrapped or displayed Non smoking home and studio Caliper photo shows length of cabochons Tough to see all the luscious colors in this light but it will pick up the colors depending on light and background and what you wear it against Way better in person, hard to get how the flash looks in all the little colors