Alexandrite is a color-change variety of chrysoberyl that appears as different colors under daylight and incandescent illumination. Pictured here is a faceted specimen of color-change alexandrite of 26.75 carats from Tanzania, showing a blue-green color in daylight and a purple-red color under incandescent light. Natural alexandrite of good color and clarity is an extremely expensive gem, however, lab-created alexandrite…

Pearl is an organic gem and the traditional birthstone for the month of June. There are three basic types of pearls: 1) natural pearls, which form naturally within the shell of a living mollusk; 2) cultured pearls, which are propagated by people by inserting a “seed” into a mollusk shell with the intent that the mollusk will deposit…

Emerald is the birthstone for the month of May. It is the world’s most popular green gem. It is the green variety of the mineral beryl. Emeralds range in color from slightly yellowish green, to pure green, to slightly bluish green. Pure green emeralds are the most popular and valuable. Emerald can be a costly gem,…

Diamond is the birthstone of April. It is the world’s most popular gem. Many people enjoy diamond because of its brilliance and because of its dispersion. Dispersion is the ability of a gem to act as a prism and separate light into its component colors – as shown by the diamond in the accompanying photo. Diamond…

Bloodstone is another gem that serves as a birthstone for March. It is an opaque green chalcedony that is marked with splashes of red and often other colors. Bloodstone receives its name from the red splashes of blood-like color. As an opaque gem, bloodstone is usually cut into dome or shield-shaped gems known as cabochons. It…

Aquamarine is the the birthstone for the month of March. Aquamarine is the blue variety of the mineral known as beryl. It occurs in a range of colors from slightly greenish blue to a nearly pure blue hue. Aquamarine also occurs in a range of color saturations, from a very light, almost imperceptible blue to a rich deep blue.…

Amethyst is the birthstone for February. It is the world’s most popular purple gem – and that enhances its status as a birthstone. The purple color of amethyst can be so light that it is barely perceptible, or so dark that a faceted gem can be nearly opaque. The color of amethyst spans a range from…

Garnet is the birthstone of January. Although many people think of a red gem when they think of garnet, it is actually available in almost every color – green (tsavorite and demantoid), orange (spessartine and hessionite), purple (rhodolite), yellow (mali and topazolite), pink (malaya), red (almandine and pyrope), black (melanite). These are just some of garnet’s…