Question about an opal ....

[Circe]

I posted this stone in another thread, but figured I should be specific to attract the attention of the opal experts. Here's the original, if you're curious ... https://www.pricescope.com/communit...ing-of-their-work-and-offered-to-swap.190320/

I know next to nothing about opals ... what would you guys call it? It looks solid with the glittering blue flashes against the grey background (which are so bright it almost looks fluorescent), but it's actually translucent, which I tried to capture in the last shot.

For example ... is it like this one? http://www.ebay.com/itm/Lightning-R...372?pt=LH_DefaultDomain_0&hash=item4ac64cd2cc

Can anybody tell me what kind of an opal this is? And if it's an okay example? I'd love to know what to look for in terms of type, quality, comparable stones, etc.

 

[chrono]

Any side views of the opal? The extra lines shown makes me suspect your opal isn't a solid piece.

 

[Circe]

Hey, Chrono! I'm pretty sure it's a solid piece - irregular and almost more like a tumbled pebble than a cab. I think that's light reflecting weirdly through the translucent material ... but I'll snap a few more in a sec. Thanks!

 

[Circe]

Let's see if the one millionth try is the charm - dunno why, but posting has been *impossible* today.

 

[peacechick]

I'm pretty sure these are boulder opals. That means they are opal formed and mixed with solid ironstone/rock, rather than being pure opal. They would be solid pieces, not doublets. Usually, they cannot be cut as cabs, so they are flat and free form, which look like the ones you have.

In terms of value, they are second to precious opal, but obviously color comes first, so the best boulder opal is basically as expensive as black opal. Among boulder opals, there are sub-varieties like Yowah and Koroit opals which I don't know about.

Here is an article comparing the differences between black opal and boulder opal.
http://www.opalsdownunder.com.au/learn-about-opals/advanced/black-opal-vs-boulder-opal

Hope this helps! I love the stone you picked! How fun that you got to pick from so many!

 

[peacechick]

I also wanted to add that imo, you picked the best stone out of the lot you received. The one you picked has no rock in it and it pops compared to the others. I think the only down factor is that it only has one color, blue, as opposed to the red/green, but it is a lovely blue

Edited to add: Here is a site with different kinds of opals and videos so you can compare them to what you have: http://www.opalsdownunder.com.au/opal-search?category=unset_opal&type=24

 

[bobsiv]

Looks like a Lightning Ridge grey/black base crystal opal to me. Defnitely not a boulder opal, it clearly doesn't have any host rock or matrix involved.

 

[bobsiv]

Forgot to add, it looks very nice although the darker black body tones are usually prefered. Looks like it's been cut very well and has an excellent polish, really pretty stone.

 

[chrono]

The side view helps a lot as I agree this is likely to be a solid piece of opal. Based on the newer pictures, I'm guessing it is not boulder opal either. What is it exactly, I am afraid I am not knowledgeable enough to say.