Real tiger’s eye as we know it
..Is a brown gemstone, masculine and elegant in appearance, with a velvety shine.
Though it’s common enough, in a way, up close it’s just as alien as the eye of a predatory animal –
there’s nothing familiar about that hard silkiness, though at first sight the color pattern is a very warm one. It suggests a violent force, withheld, controlled, hypnotic like Jupiter’s surface.
It seemed mysterious and unfriendly to the writer L. Frank Baum, who, strongly impressed, pictured it as a sentient eye, a living soul trapped in a world of cruelty and violence; this eye serves a tiger, the human who kills it, and even a deer which instantly becomes bloodthirsty against its nature.
This tale helps to bring mystery to one of quartz’s many faces, and partly explains the ancient practice of cutting it into eyeballs for skulls and sculptures made of other materials.
The first thing we notice is the stripes (just like its spirit animal); they are not mandatory
but they are frequent as an alternation of dark and light bands. Also, the gemstone proper can be interspersed
(or not) with various types of matrix. The most desired is bands of opaque, interrupted haematite, which creates an even more martial combination named tiger iron.
But let’s look closer into it:
As always, understanding its nature is the key to recognizing the true from the fake.
Tiger’s eye is, just like opal, a silicon dioxide. It is formed, just like opal, on former crocidolite fibers (best known to you as asbestos, a blue form).
The difference here is the shape. Where opal is amorphous, tiger’s eye is crystalline (a form of quartz).
The silica keeps to the parallel fiber structure of the asbestos, adding a light play known as “chatoyant” (from French Chat = Cat). This is arguably not the same as the Cat’s Eye effect; they’re both owing to the same fibrous structure, the difference being that chatoyance is velvety, irregular, because of sinuous fibers, while cat’s eye is more diffused and uniform, silky, with straight fibers.
Also, the light focus on a chatoyant stone moves with the lightsource; in cat’s eye, it doesn’t move and can be seen in the same position from all angles.
Some authors think this is the same thing. Sometimes, Tiger’s eye can display cat’s eye, further stating the similarity of these effects.
So with this, it’s easy to know where you stand: it’s either chatoyant or it’s not.
In regards to the color:
It’s easy too, but to understand it, let’s see about genesis: Tiger’s eye is a pseudomorph, meaning it steals the shape of another crystal. It has its own microcrystalline structure (being a quartz), but it takes over crocidolite’s fibrous shape as well.
There are two possibilities:
- the silica dissolves the base mineral entirely, creating the honey to brown to red iron oxide coloration;
- the dissolution is incomplete, where crocidolite is not decomposed and its grey or blue color is still apparent. This is actually called Hawk’s Eye.
As you understand from this process, it is possible and probable to have combination and superposition of colors.
The enemy here is treatment.
Often, dull pieces can be dyed or bleached to get a red, maroon, blue or golden hue. The treatment is apparent if you’re used to the natural color; the natural color varies in intensity,
but a lot less in hue (see a description here).
When this is said and done, you will know tiger’s eye when you see it. The good thing is, it’s common enough to be cheap; an elaborate imitation doesn’t exist, and a different mineral would be way more expensive than the real one. The only cheap thing that could come close is fiber optics and maybe some plastics; but plastics are easy to tell apart by the little secrets you already know, and glass can be scratched (tiger’s eye has a hardness of 6-7, where a diamond is a 10 and glass is.. a lot less).
Best advice to tell real tiger eye:
Check it’s a mineral and not a plastic, then look carefully. The color can be faked, but the chatoyance cannot. It’s important not to buy a gross imitation; apart from that, it’s cheap enough so that beauty should be the only important aspect.
Remember: on the contrary, if the piece is expensive, always ask for credentials and check with an expert. This is the only way to tell for sure.