Golden-brown with a moving band of light. Quartz that replaced a fibrous mineral.
Every continent — the commonest mineral in the crust2 references
Tiger's eye is quartz that has grown through and replaced a fibrous mineral, keeping the fibre structure. Light reflecting off those parallel fibres produces chatoyancy — a band of brightness that slides across the stone as it tilts, the same effect that gives a cat's-eye gemstone its name.
The moving band is the identification and it is very hard to fake convincingly in natural materials. Manufactured fibre-optic glass, sold as 'cat's eye' beads in bright unnatural colours, does produce a band, but the band is razor-sharp, dead straight, and identical on every bead in the strand. Tiger's eye's band is softer, slightly irregular, and varies piece to piece because the fibres do.
Blue material is called hawk's eye and is the less oxidised form. The vivid red tiger's eye on the market is almost always the golden variety gently heated, which converts the iron to a red oxide. That is a long-accepted treatment rather than a fraud, but again, it should be said.
Blue 'hawk's eye' · Red tiger's eye (usually heat-treated)
Establish which of these you are holding before judging it. A genuine piece read against another reference's rules will look wrong when it is not.
These apply to this model and not to the rest of Quartz. Work them alongside the maker's general checks, not instead of them.
Rock the stone slowly under a single light source. The bright band should sweep across the surface perpendicular to the fibre direction. No band, no tiger's eye — a plain brown banded stone is more likely jasper or a dyed quartzite.
A natural chatoyant band wavers a little, changes width along its length, and differs between pieces cut from the same rough. A perfectly straight, uniform, needle-sharp band repeated identically across a whole strand of beads is fibre-optic glass.
It is quartz, so it scratches glass and resists a knife. Dyed and stabilised imitations built on softer stone fail this immediately.
A few dollars for tumbled pieces; slightly more for well-oriented cabochons with a sharp band.
An orientation for honest, unrestored condition — never an appraisal, and never a quotation.
Lovenhall StoneThe tests tell you what it is. The instrument reads a photograph and offers a name to start from — then hands you back to the tile and the coin, which are what settle it.