Tourmaline with tiny parallel inclusions sometimes display a strong cat's eye effect when polished. The cat's eye or chatoyancy effect is most easily seen in strong light, especially in sunlight. Cat's eye tourmaline stones are usually found in pink and green. They are not uncommon but can be difficult to find, making them of interest to collectors. Since tourmaline cat's eyes are usually cut as cabochons, one can often find fairly large pieces.
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