There are all sorts of gemstones out there. Not surprisingly, many of these gemstones are somewhat related to each other, because they are often simply varieties of the same mineral. One such gemstone is Hawks Eye, which we affectionately recognize as Tiger Eye’s grey brother. Hawks Eye is a blue grey to blue green variant of macrocrystalline quartz. This special variety is achieved through the pseudomorph nature of Hawks Eye. Pseudomorph refers to the transformation of one mineral to another over long periods of time. Hawks Eye is a pseudomorph of macrocrystalline quartz. It began life as the mineral crocidolite and slowly transformed into Hawks Eye over time. Crocidolite is one of the many forms of asbestos, with a blue, fibrous composition. It gradually achieves the transformation to quartz when quartz begins to embed itself between those fibers, slowly replacing the entirety of the gemstone while still maintaining its shape and texture.
Hawks Eye has many sources across the world, including Burma, Spain, South Africa, Australia, China, and many others, but the most notable deposits, and the largest commercial suppliers of Hawk Eye, are located in Thailand and the Northern Cape province of South Africa.
Ironically, rather than calling Tiger Eye the brother of Hawks Eye, it may be better to say that Hawks Eye is the parent of Tiger Eye. After all, Tiger Eye is actually derived from Hawks Eye. The transformation of crocidolite to quartz leaves behind oxide: if there is less iron left over, you get the typical blue of the transformation, but less iron results in the golden brown color that defines Tiger Eye. In the end, they are simply variants of the same thing. That said, one of the biggest distinctive differences in Hawks Eye and Tiger Eye is their colors. While Tiger Eye is a distinctive brownish gold, Hawks Eye is more grayish blue. As explained earlier, Hawks Eye also has less iron in it than Tiger Eye, hence the color it has.
Still, when considering Hawk Eye, it’s important to keep in mind that they are often a variety of different colors, and even though they tend to be primarily bluish gray or blue green, they can still have notable streaks of golden brown in them, and the stones themselves often bear multiple colors across their surface regardless. Whether or not this affects their worth is up to the individual’s personal preference, but the presence of gold or brown in Hawk Eye does not indicate defectiveness in any way. Streaks of golden brown are usually the result of a slightly higher level of iron in that particular area.
For the record, the majority of Hawks Eye gemstones are not treated in any way. However, some can be dyed for darker colors, or treated with nitric acid to lighten their colors. Gem dealers will almost always notify you if such enhancements have been used on a Hawk Eye gemstone, but if you need the extra peace of mind, you can always ask.
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