It’s the color-change variety of the mineral, chrysoberyl. Bluish green in daylight, purplish red under incandescent light; hard and durable. Top quality examples are rare and valuable.

Fossilized resin, color of the burnished sun–orange or golden brown. Amber might trap and preserve ancient life, including insects, leaves, even scorpions and occasionally lizards.

Purple variety of the mineral quartz, often forms large, six-sided crystals. Fine velvety-colored gems come from African and South American mines. In demand for jewelry at all price points.

Ametrine, one of the rarest types of transparent quartz, combines two colors: amethyst’s purple and citrine’s orange-to-yellow, growing together in a single crystal.

Blue to slightly greenish-blue variety of the mineral beryl. Crystals are sometimes big enough to cut fashioned gems of more than 100 carats. Well-formed crystals might make superb mineral specimens.

Citrine is the transparent, pale yellow to brownish orange variety of quartz. Citrine’s color comes from traces of iron. It’s perhaps the most popular and frequently purchased yellow gemstone and an attractive alternative for topaz as well as for yellow sapphire.

This hardest gem of all is made of just one element: carbon. It’s valued for its colorless nature and purity. Most diamonds are primeval—over a billion years old—and form deep within the earth.

Fine color diamonds are the most rare and costly of all gemstones. Only one in 10,000 diamonds has a fancy color. Their ranks include the world’s most famous jewel—the Hope—and the most expensive gem ever auctioned—The Graff Pink.

The most valued variety of beryl, emerald was once cherished by Spanish conquistadors, Inca kings, Moguls, and pharaohs. Today, fine gems come from Africa, South America, and Central Asia.

The garnet group of related mineral species offers gems of every hue, including fiery red pyrope, vibrant orange spessartine, and rare intense-green varieties of grossular and andradite.

Known in the jewelry trade as iolite, this mineral is known as cordierite to geologists and mineralogists. It was named after French mineralogist Pierre Cordier.

Jade is actually two separate gems: nephrite and jadeite. Prized by civilizations from ancient China to the Aztecs and Mayans of Central America, jade is crafted into objects of stunning artistry.

Trace amounts of manganese give this pink to violet variety of spodumene its feminine glow. A relative newcomer to the gemstone stage, kunzite was only confirmed as a unique variety of spodumene in the early part of the twentieth century.

Lapis is a beautiful rock; an aggregate of several minerals, mainly lazurite, calcite, and pyrite. Lapis lazuli is treasured for its beautiful deep blue color. Afghanistan is considered the source of the best-quality lapis.

Feldspar prized for its billowy blue adularescence, caused by light scattering from an intergrowth of microscopic, alternating layers. Favored gem of many Art Nouveau jewelry designers

Like its cousins emerald and aquamarine, morganite is a variety of the beryl mineral species. This gem gets its subtle blush when a trace amount of manganese makes its way into morganite’s crystal structure.

Fireworks. Jellyfish. Galaxies. Lightning. Opal’s shifting play of kaleidoscopic colors is unlike any other gem. Opal’s microscopic arrays of stacked silica spheres diffract light into a blaze of flashing colors. An opal’s color range and pattern help determine its value.

Produced in the bodies of marine and freshwater mollusks naturally or cultured by people with great care. Lustrous, smooth, subtly-colored pearls are jewelry staples, especially as strands.

Yellow-green gem variety of the mineral olivine. Found as nodules in volcanic rock, occasionally as crystals lining veins in mountains of Myanmar and Pakistan, and occasionally inside meteorites.

Rose quartz is a quartz variety that gets its name from its delicate pink color. Microscopic mineral inclusions cause the pink color and translucence of rose quartz. Well shaped, transparent pink quartz crystals are rare.

Ruby is the most valuable variety of the corundum mineral species, which also includes sapphire. Traces of chromium give this red variety of the mineral corundum its rich color. Long valued by humans of many cultures.

Depending on their trace element content, sapphire varieties of the mineral corundum might be blue, yellow, green, orange, pink, purple or even show a six-rayed star if cut as a cabochon.

Although frequently confused with ruby, spinel stands on its own merits. Available in a striking array of colors, its long history includes many famous large spinels still in existence.

Named for Tanzania, the country where it was discovered in 1967, tanzanite is the blue-to-violet or purple variety of the mineral zoisite. It’s become one of the most popular of colored gemstones.

Colorless topaz treated to blue is a mass-market gem. Fine pink-to-red, purple, or orange gems are one-of-a-kind pieces. Top sources include Ouro Prêto, Brazil, and Russia’s Ural Mountains.

Comes in many colors, including the remarkable intense violet-to-blue gems particular to Paraíba, Brazil, and similar blues from Africa. Favorite of mineral collectors.

Ancient people from Egypt to Mesoamerica and China treasured this vivid blue gem. It’s a rare phosphate of copper that only forms in the earth’s most dry and barren regions.

Optical properties make it bright and lustrous. Best known for its brilliant blue hues; also comes in warm autumnal yellows and reddish browns, as well as red and green hues.