Colorful Inclusions in Diamond
Inclusions can be found in a variety of different gemstones; they create a window that allows the viewer to picture a stone’s formation history. Diamond possesses the ideal characteristics for preserving these features. Chemically inert and durable, it is the perfect host for inclusions.
In general, inclusions in gem diamonds are considered undesirable. While extremely common in a number of forms, they almost always lower the clarity grade of a diamond to varying degrees depending on their type, size, quantity, and location. This happens because they are “imperfections” within the crystal that can ultimately affect the way light interacts with the stone, detracting from the overall brilliance of a properly faceted gem. In some cases, however, inclusions can make a diamond uniquely special.
Recently the New York lab examined two gem-quality diamonds (figure 1) possessing vivid green and purplish pink inclusions. With Raman spectroscopy, the green inclusions were identified as enstatite and diopside while the purplish pink inclusion was identified as pyrope garnet (figure 2). Both are common in ultramafic rocks, typically from a peridotite host. Chromium, an element characteristic of the earth’s very deep rocks, is the chromophore responsible for both the green and the pink within these different minerals. The different lattice environments within these minerals results in distinct octahedral Cr-O bond lengths, and therefore they differ in light absorption and color produced. The vivid green color and shape of the diopside and enstatite are similar to those of the inclusions captured in The Microworld of Diamonds: A Visual Reference Guide, by John I. Koivula (Gemworld International, Northbrook, Illinois, 2000). As these diamonds formed, they enveloped the inclusions.
It is rare to see such high-quality diamonds with these types of inclusions. These timeless diamonds possess valuable relics of Earth’s beginnings, making their clarity features noteworthy.
