Hawk's Eye
Last updated: April 2026
Blue-grey to blue-green chatoyant quartz formed where crocidolite asbestos is replaced by silica without iron oxide oxidation (which produces golden Tiger's Eye). The retained blue color of the asbestos gives Hawk's Eye its steely blue-grey to greenish-blue hue. Always cut en cabochon. Often found alongside Tiger's Eye in the same host rock.
Physical & Optical Properties
RI Range1.544–1.553
SG Range2.64–2.71
SG Typical2.65
Hardness (Mohs)7
Crystal SystemTrigonal
Optic CharacterAggregate
Dispersion0.013
Fluorescence LWInert
Fluorescence SWInert
Chelsea FilterInert
PleochroismNone
ColorsBlue Violet, Green
SpeciesQuartz
Related: Quartz Varieties
Key Differentiators
- Blue-grey to blue-green color from unoxidized crocidolite (unlike golden Tiger's Eye)
- Chatoyancy (cat's eye effect) from parallel fibrous structure
- Silky luster; fibrous pseudomorphous quartz after blue asbestos
- Inert under UV; quartz RI and SG identical to Tiger's Eye
Treatments
- Dyed Tiger's Eye to resemble Hawk's Eye
Price Context
Natural — low ($/ct)$1
Natural — high ($/ct)$15
NotePer carat; less common than Tiger's Eye; value driven by depth and uniformity of blue color and chatoyancy quality
Price context is approximate. GemID is not an appraisal tool. Results are indicators, not certified valuations.
Measurement Guides
Identifying a hawk's eye? GemID walks through these tests in order — RI, SG, fluorescence, and more.
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