Curious about this opal.

Hi.

I am quite curious about this opal and the value of it.

I have never before seen this pattern or the sort of waves in the fire pattern.

The waves are not from crazing (Cracks) but actually patterns in the Opal.

It is also not synthetic as I cut the opal myself from the rough nodule, which still had bits of the dark matrix attached to it.

This is an opal from Ethiopia that I bought last weekend.

I don't know the exact carat weight but as you can see, it is thumb sized.

It's very strange in many ways.

First, the very bottom part of the opal is clear crystal opal (This was the bottom of the nodule). It's not a doublet or what have you, just naturally crystal for like 10% of the height of the stone.

Second, it has this weird ring effect in the colour pattern of the opal. It's like the undulation of cloud bottoms. (As can be seen especially in the photo with the backlighting.

Third, it has a unique pattern of fire, kind of like a tortoise shell, with smaller patches in the centre and spreading out to larger patches.

This is a 100% natural, non-treated opal.

And fourth, this is a 'Hydrophane' opal.

When left in the water for ten minutes, it will absorb the water (Non-damaging to the opal by the way) and become crystal clear, with sheets of colours.

So, if anyone that has knowledge can help me in a rough estimate of the value, I would be really grateful.

Thanks

A friend who may see this and comment has a great interest in opals and forever complains that this or that photo doesn't really do justice to the stone. From your photos we can see it has good colours and isn't a doublet, but I doubt that opals can be properly valued from photos.

Thanks for the response : )

It took about...

Too many photos to finally get some nice photos. lol

I will weigh it tomorrow when I can use my friend's scale to see how many carats.

If I get enough responses on this board like 'I think it seems quite valuable (A few hundred Euros or so)', then I might take it to a Certified Gemologist here to get an appraisal and paper.

I am thinking that because I cut it out of a whole nodule, the circle patterns may be perhaps some kind of growth patterns.

I even think perhaps that the fire pattern looks like maple leaves connected together : )

Here are more photos : )

Beautiful opal Bri, nice cutting and polish. Id say the circle patterns certainly do have some relationship to the nodules shape and growth. Before we talk about value, its important to check its stability, In other words, is this material likely to craze and crack, will any small inclusions turn into large white puff balls , etc, in other words is it stable. This has to be all checked, before there is any thought about selling , or price. Assuming the stone has passed these tests, I would say material with similar color and appearance, would cost at least $50 per caret , in any shop selling opal , here in Australia.......Greg

Regardless of where it is from, it will probably bring at least several hundred Euros. However Ethiopian opals are notorious for their high water content and cracking during cutting or after a short period of time. The fact that you managed to cut is at all is remarkable. Perhaps they found a new locality. I, for one would not want to buy a cut stone from Ethiopia unless the stone had been out of the ground for several years and not stored in water or oil.

Rock Currier
Crystals not pistols.

This year my friend and i we by some ethiopian rough opal, like your quality, but some piece are water sensible. Your quality for example, if you put the opal under the water come jelly or very transparent. After one hour come milky, after one or two mounts come semi transparent like your opal in photo.
Whene i cut the opal i see more changes. These opals are very beautiful, is possible see beautiful color and internal structures but are very fragile.

This is the kind of stuff that needs to go into the Best Minerals article on Opal. Anyone want to take on the challenge of writing the Best Minerals Opal article?

Rock Currier
Crystals not pistols.

But Opal isn't a real mineral!

(runs away and hides)

Be careful Jolyon, The CNMNC of IMA police will find you (opal has status G on their list).

It's just damp quartz. They'll be saying obsidian is a mineral next. Or mercury

Jolyon

Mercury is a fine old example of a mineral species that probably goes back to Pliny, the Elder or earlier. Next you'll be telling me that water isn't a mineral!!! Of course air is a mixture and so it can't be a species.

I just wanted to thank everyone for your replies

I was reading that this material is quite stable and is very very dry.

It was my first opal that I cut actually.

I cut it using sand paper and then polished it with Carborundum Grit, from size 220 til 800 and then the final polish with Aluminium Oxide polishing powder. All of the polishing was done with a Dremel-type machine and 'Felt' polishing heads using cooking oil mixed with the powders as a slurry.

-Bri

Hi Bri, i cut some rough opal like as you do, but for polishing i used oil and diamond powder. After few days opal come white and opaque, and some color go out. How many days, weeks or mounts you had cut the opal?

Hi Alessio : )

It's been since Saturday since I cut the material, so I would so it has been cut for 5 days or so.

I have seen some of the Ethiopian material crack (Craze) in some of the polished pieces but also, on the new material coming out (The crystal opal material like this one), there seems to be almost no cracking.

Because the opal is Hydrophane (To go clear in water), I made sure not to use any water when I was cutting and polishing it.

I bought the rough material out of a dry box so I think the opal has been dry for a long time.

I was also very careful to not use too much heat when I was polishing it. I never let the temperature of the stone get much more hot than my fingers.

I also checked the stone as I was polishing by putting a light under the stone to see if it was cracking during polishing.

I did drop it one time while polishing it and had to re-polish it to remove a small crack.

I am curious about the opal that some people complained about from Ethiopia that it was cracking.

I wonder if it was bought while it was in water or if it had not been dried out properly or not polished well. (Too much heat or something.)

Would you please put a photo of the opal you cut on here? : )

I am curious how it looks.

I am thinking that when you bought it, maybe it was not totally dried by the dealer or something.

Then when you cut it, the water that was left inside finally left and made it more milky white.

I know that other Hydrophane opal (Like the kind from Australia that is Hydrophane.) is only milk white and chalky and shows no colour but when it is put in water for awhile, it turns more clear and shows colours but goes back to white when dried.

-Bri

I am thinking that when you bought it, maybe it was not totally dried by the dealer or something.


Hi Bri, probably that my opal not more dry, because some opals, i cut it without water. Tomorrow i down load the photo of my opal.

Hi Bri, these are my opals.

You can see the different, the long oval cut on the left side is cut with water and polished with cerium oxide, the free form cut on the right side is cut without water and polished with oil and diamond powder.

In the other photo you can see the pre-polished oval cut, and you can see the "internal opal structure".

Three suggestions. I'm not an opal dealer, so grain of salt, blah, blah.

1) You can't put a value on it till it's been out of water for a decent period of time. Research the stuff. Opal is a major gem and I'm positive somebody has written about this find somewhere. If it should be stable after a year, then there you go, put it in a drawer for a year. I've heard the Australian miners leave their rough out on the tin roof for a summer, if it survives that it'll survive anything.

2) There's lots of Ethiopian opal available on the web. Should be easy to compare size, fire, value. The fire pattern may bring a premium, but it's not going to be an order of magnitude difference or anthing like that, in my opinion.

3) After a year, if it's proven stable, take it to a gemologist that you trust. And remember there are lots of different possible values: what he'd pay you for it, what he'd sell it for in a nice gold setting, what it'd bring at auction, what it should be insured for, etc.

Cheers,

T

Just adding a new photo for those who like to see such things

Yes, I know about the problem with opals cracking, etc (Crazing).

For sure, that can be a problem.

If you search for Opal jewelry from Lalique, you can see most of the opals that he used have crazed in time

If I remember right, those Opals were from Hungary I think.

So, they actually crazed probably many years after being set in jewelry.

I only would ever buy opal that is dry, never the things hanging about in water.

Well, we will see how long this one lasts

Here in Florida we have several regional dealers (one who is from Ethiopia) who sell rough and cut Ethiopian opal at local shows. All of it is stored and sold dry. Prices for rough vary from $5 to $25 per carat, based on the quality and amount of fire (which can be considerable). The orange pieces (when cut) have the reputation of crazing easily. In fact I saw several such pieces recently that a dealer had to buy back.

I bought a few very colorful rough pieces of white opal, and a few somewhat less colorful pieces of orange opal. The white sticks to the tongue while the orange doesn't. The white opal becomes less transparent and colorful when soaked in water. (The variety of opal that Bauer calls hydrophane also sticks to the tongue, but increases in fire and transparency when soaked.)

I've heard some dealers say that Ethiopian opal is unreliable unless stabilized. Overall, it looks spectacular, but its durability seems suspect.