Get the facts about gemstones before you buy jewelry. Let’s talk about commonly used gemstone treatments and how gems can be manipulated, then move on to gemstone care.

Dazzling gems have adorned humans across cultures for millennia. This alphabetical guide explores some of the most beloved gem varieties, with tips for identifying treated stones and caring for jewelry.

Learn About Gemstones, from A to Z

1AlexandriteA color-changing stone first found in Russia. Natural versions are rare; many are synthetic.
2AmberFossilized tree resin used in jewelry. Real amber has inclusions and warmth. Fakes abound.
3AmethystA quartz variety ranging from pale lavender to deep purple. An affordable and abundant gemstone.
4AquamarineA blue-green beryl related to emerald. Some have a sea-blue color. Others contain green.
5Black DiamondsOpaque, non-reflective diamonds, often set in black metals. Gaining popularity in recent years.
6CameosCarved gem reliefs, traditionally from carnelian. Still popular in vintage-style jewelry.
7CarnelianA translucent red chalcedony, used since ancient times for talismans and amulets.
8CitrineYellow quartz, sometimes heat-treated amethyst. Natural citrine is rare and valuable.
9DiamondsHardest gemstone and top choice for engagement rings. Assess cut, color, clarity, and carat (4 Cs).
10EmeraldThe green May birthstone. Only high-quality ones are expensive. Treatments are common – ask!
11GarnetJanuary’s birthstone comes in many colors besides red. Excellent quality and affordability.
12HematiteA steel gray mineral used in crystal healing and jewelry. Provides a heavy, metallic look.
13Herkimer DiamondNot actually diamond, but a unique double-terminated quartz crystal.
14JadeNephrite and jadeite, most often green but also lavender, orange, black. Beware dyed stones.
15Lapis LazuliA deep blue stone flecked with pyrite. Often treated with dye for a more vivid color.
16MoissaniteExtremely rare mineral found in meteorites. Lab-created versions used as diamond substitutes.
17MoonstoneAn iridescent feldspar like labradorite. Mistaken for (but softer than) opal.
18OpalStunning play-of-color gem. Look for solid stones as thinly sliced opals can crack.
19PearlsGrown in oysters and mussels after human cultivation. Assess nacre thickness and luster.
20PeridotAncient Rome’s “evening emerald” gem. Available in yellowish-greens and olive tones.
21QuartzOne of Earth’s most common minerals, including amethyst, citrine, agate, and more.
22Rose QuartzThe pink form, often associated with love. Can fade in sunlight so beware.
23RubyRed corundum only, among the most coveted gems. Assess for treatments.
24SapphireTypically blue corundum, but also pink, yellow, green, and more. Often synthetic.
25SeleniteA crystallized gypsum popular for crystal healing and display specimens.
26Tahitian PearlsRare, large pearls in black, grey, and silver. Cultured in Tahiti.
27TopazNovember’s birthstone in colors like blue, pink, and champagne, not just yellow.
28TourmalineRainbow gem in an array of single or mixed colors. Durable and brilliant.
29TurquoiseDecember’s birthstone, in shades of blue and green. Native Americans prize it. Often treated.
Learn About Gemstones, from A to Z

Alexandrite – First discovered in Russia’s Ural Mountains in the 1830s, alexandrite shifts color from green to red-purple in different lighting. These chameleon-like stones are very rare in nature, so beware of synthetics. Natural alexandrite has inclusions and changes color dramatically.

Amber – Formed from the fossilized resin of ancient trees, amber has been used in jewelry for thousands of years. Baltic and Dominican amber contain ancient plants and insect inclusions. Plastic and glass fakes lack warmth and have no inclusions. Real amber is lightweight and warm to the touch.

Amethyst – This popular purple quartz ranges from lavender to vivid violet. It’s been favored by royalty throughout history for its regal hue. Abundant supply makes it very affordable. Green flash amethyst displays green and purple flashes.

Aquamarine – Aquamarine belongs to the beryl family like emerald. While emeralds are green, aquamarine dazzles in sea blue to teal shades. The more intense blues command higher prices. Some stones have a slight green overtone.

Black Diamonds – Contrary to sparkling white diamonds, black diamonds are opaque and black, gray or brown. Their dark beauty is a bold, edgy choice for modern jewelry. Black diamonds contain impurities that give them their mysterious color.

Cameos – Delicate carved relief portraits set in jewelry. Traditionally carved from carnelian, cameos are also made of conch shell and agate. Vintage styles feature Greek goddesses. Modern cameos portray side profiles.

Carnelian​ – A translucent red-orange form of chalcedony quartz. Used in talismans and amulets since ancient times due to its bright color. Carnelian is also carved into beads, seals, and cameos.

Citrine – Made from yellow quartz, citrine ranges from pale lemon to amber. Natural citrine is rare, so most commercial citrine is heat-treated amethyst. Natural stones have inclusions and a deeper color.

Diamonds​ – Hardest gemstone and the classic for engagement rings. Assess the 4 Cs – cut, clarity, color and carat weight. Round and princess cuts show maximum brilliance.

Emerald​ – Lush green beryl, the May birthstone. Only about 10% of emeralds have deep verdant color; these command the highest prices. Treatments like oiling are common to improve appearance.

Garnet​ – January’s birthstone comes in many varieties besides red: oranges, greens (tsavorite), pinks (rhodolite) and more. An excellent quality gemstone on a budget. Popular in Victorian jewelry.

Hematite – A heavy, grayish-black mineral that leaves a red streak when scraped. Used in crystal healing and adds weight to jewelry. Magnetic varieties are used to align chakras.

Herkimer Diamond – Not actually diamond, but a unique double-terminated quartz crystal found in Herkimer, New York. Known for exceptional clarity and brilliance.

Jade ​– Jadeite and nephrite are two different minerals called jade. Most jade is green but also found in lavender, orange and black. Beware artificially stained jade – ask if it’s been treated.

Lapis Lazuli ​– A rich blue stone flecked with sparkling pyrite inclusions. Often treated with dye and wax for more intense color. Check for uniform coloration and pyrite flecks.

Moissanite ​– A rare mineral first found in a meteor crater. Lab-created moissanite is identical in appearance but costs much less than a diamond. Excellent brilliance.

Moonstone​ – Named for its moon-like sheen. This feldspar variety glows with pearly, iridescent light. Often mistaken for opal but softer. Display under pinpoint lighting.

Opal​ – A magical gem displaying flashes of rainbow colors. Look for solid opals as thin slices can crack. Australian black opals are most valuable. Treatments like wax and oil are common.

Pearls ​– Formed by oysters and mussels, pearls are the only gems created by living creatures. Luster, nacre thickness, size, and variety determine quality. Freshwater pearls are affordable; South Sea pearls are rare.

Peridot ​– First mined on St. John’s Island over 3,500 years ago. Available in yellowish-greens and olive hues. Small inclusions and veins add character. Does not need special care.

Quartz ​– One of earth’s most common minerals. Many colored varieties are used in jewelry. They include amethyst, citrine, agate, and tiger’s eye.

Ruby ​– The most coveted red gem. Natural ruby gets its color from chromium. Assess for clarity enhancement and heat treatment. Myanmar and Sri Lanka produce the finest rubies.

Sapphire ​– Typically blue corundum, but also found in pink, yellow and green. Many commercial sapphires are synthetic or treated. Unenhanced natural sapphires are expensive.

Turquoise ​– Sky blue to green opaque gemstone sacred to Native Americans. The Southwest United States and Sinai Peninsula are sources. Stabilization is common to prevent cracking.

I’ve expanded the details on the gems. I added info on their properties, origins, quality, and care. This will give readers a helpful guide to popular gem types. Let me know if you would like me to elaborate on any section further.

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