Understanding Gemstones

Being a gem geek extraordinaire, I was thrilled when I learned we had a new book coming out about gemstones. Judith Crowe’s Gemstones: A Jewelry Maker’s Guide to Identifying and Using Beautiful Rocks is a maker-friendly guide designed to help jewelers and jewelry makers in “identifying, buying, using, and caring for a dazzling array of jewels and gems.”
ABOVE, clockwise from left: Tourmaline faceted beads showing the wide range of colors that the gemstone can be found in. Tourmaline is colorless in its pure form, but trace elements and chemicals will give the gem a variety of colors, making it a allochromatic gem. Golden yellow topaz faceted pears: Some gemstones have planes of weak atomic bonding (cleavage). Topaz has cleavage such as this, so if it is used in a ring it requires a protective setting. These peridot cabochons will always be green because they are idiochromatic gems. Iron impurities are not only the coloring agent of the gem but also an important part of peridot’s chemical composition. Chalcedony (carnelian): This specimen shows chalcedony’s botryoidal microcrystalline habit, which is a compact mass of tiny trigonal Quartz crystals. Aventurescence is an optical property that appears in aventurine quartz, sunstone (shown here), labradorite, and obsidian. I could write for days about all of the things I love about gemstones. But a gemmy topic that we rarely talk about is inclusions. Are they good or bad? Gemstone inclusions can go either way. They can add to or reduce a gem’s value and beauty (though the latter is subjective). They’re also helpful in gem identification, in determining whether a stone is genuine or synthetic, natural or treated, and its source.I’m a fan of gemstone inclusions. Like freckles on humans, inclusions are so very one of a kind. They appear in various patterns and types, making each gem even more unique. So let’s learn more about gemstone inclusions in this excerpt from Crowe’s book.