By Christopher P. Smith, American Gemological Laboratories
Spinel has historically been one of the most highly revered gemstones. However, over an extended period of time, its popularity had suffered as a result of many factors, including its classification as “semi-precious” and a general confusion with another dominant red gemstone: ruby. More recently though, spinel has been making a strong comeback and so its popularity is once again on the rise.
Articles of important new
sources and even a book devoted to this beautiful and colorfully diverse
gemstone have helped to focus attention back onto spinel (see e.g.
Smith et.al., 2007; Senoble, 2008; Pardieu et.al., 2009; Krzemnicki,
2010; Yavorskyy and Hughes, 2010). In addition to exhibiting a vibrant
array of shades and nuances of color, spinel has also traditionally been
spared the controversy of treatments that have encumbered many other
gem varieties, such as ruby, sapphire, emerald, quartz, topaz and
tanzanite among others.
Fortunately, spinel remains a gemstone that is generally free of treatment considerations. However, today some treatments are starting to be encountered (Robertson, 2012). This article is a review of those treatments and the gemological characteristics that help to distinguish them.