The Sidney Thomas Jewelry Guide offers information about fine jewelry. When selecting a diamond engagement ring or other diamond jewelry, consider reviewing our diamond jewelry guide, prepared by our world-class gemologists. It contains information on cut, clarity, carats and color. You can also find key insights about sapphires, rubies and emeralds, as well as pearls, amethyst, turquoise and other gemstones. No matter what you're shopping for, you can make an informed decision using our expert resources.