Gemstone Education
Gemstone Education
Explore the Colorful World of Gemstones
Gemstones have been admired, traded, worn, and treasured for thousands of years. Each stone has its own combination of hardness, toughness, color, rarity, origin, treatments, and cultural history.
Some are traditional birthstones, while others are valued for their unusual colors, optical effects, history, or connection to a particular jewelry style.
Explore the guide below to learn more about gemstones and discover gemstone engagement rings and other gemstone jewelry.
Explore the Gemstone Guide
Gemstone Basics
Birthstones by Month
- January: Garnet
- February: Amethyst
- March: Aquamarine
- April: Diamond
- May: Emerald
- June: Pearl
- June: Moonstone
- June: Alexandrite
- July: Ruby
- August: Peridot
- August: Spinel
- September: Sapphire
- October: Opal
- October: Tourmaline
- November: Citrine
- December: Blue Topaz
- December: Turquoise
- December: Tanzanite
Additional Gemstones & Materials
Hardness & Toughness
Hardness and toughness describe two different aspects of a gemstone's durability.
Hardness
Hardness is a gemstone's resistance to scratching. The Mohs scale ranks minerals from 1 to 10, with diamond at the top.
Toughness
Toughness is a gemstone's resistance to breaking, chipping, or cracking. A gemstone can be very hard but still relatively vulnerable to impact.
Overall Durability
Durability also depends on the gemstone's cut, setting, size, inclusions, and the type of jewelry in which it is used.
For more information about caring for different gemstones, read our Ultimate Guide to Gemstone Jewelry Care.
What Makes a Gemstone Valuable?
Gemstone value is not determined by a single characteristic. Several factors can influence what a particular stone is worth.
Color
Color is often one of the most important factors. Hue, tone, and saturation can all affect how desirable a gemstone is.
Clarity
Clarity describes inclusions and blemishes. Their effect on value depends on the gemstone. Some stones are prized even when naturally included.
Cut
A well-executed cut can improve a gemstone's color, brilliance, sparkle, and overall appearance.
Carat Weight
Larger gemstones can be rarer, but carat weight alone does not determine quality or value.
Rarity & Origin
Unusual colors, sizes, qualities, or geographic origins can make some gemstones particularly rare and desirable.
Treatments
Treatments can improve a gemstone's appearance or stability. The type of treatment and its effect on care and durability can influence value.
Gemstone Treatments
Many gemstones are treated to improve their color, clarity, durability, or overall appearance. Common treatments include heating, fracture filling, diffusion, irradiation, dyeing, and surface coatings.
A treatment is not automatically a negative characteristic. The important questions are what treatment was used, how permanent it is, how it affects the gemstone, and whether it changes how the stone should be cared for.
Because treatments vary considerably from one gemstone to another, proper identification and disclosure are important when evaluating a gemstone.
Gemstone Jewelry Care
Different gemstones require different levels of care. Hardness, toughness, treatments, inclusions, and even the gemstone's setting can affect how it should be cleaned and worn.
Learn more in our Ultimate Guide to Gemstone Jewelry Care.
January Birthstone: Garnet
Garnet is best known for its rich red color, but the garnet family includes stones in orange, green, pink, purple, and other colors. Its broad color range makes garnet one of the more varied traditional birthstones.
| Mohs Hardness | 6.5–7.5 |
|---|---|
| Toughness | Generally good |
| Common Colors | Red, orange, green, pink, purple |
Garnets have been used in jewelry for thousands of years. Ancient examples have been found in jewelry and decorative objects, and red garnet varieties were particularly popular throughout history.
February Birthstone: Amethyst
Amethyst is the purple variety of quartz. Its color can range from delicate lavender to deep, saturated purple, and its combination of color, durability, and availability has made it a popular jewelry gemstone.
| Mohs Hardness | 7 |
|---|---|
| Toughness | Good |
| Common Colors | Lavender to deep purple |
The name amethyst comes from the ancient Greek word amethystos, meaning “not intoxicated.” Ancient Greeks associated the gemstone with protection from drunkenness, and amethyst has had a long history of association with sobriety and protection.
March Birthstone: Aquamarine
Aquamarine is the blue to blue-green variety of the mineral beryl. Its name comes from the Latin phrase for “water of the sea,” reflecting its characteristic watery color.
| Mohs Hardness | 7.5–8 |
|---|---|
| Toughness | Good |
| Common Colors | Blue to blue-green |
Aquamarine has long been associated with the sea. Historical traditions connected it with sailors and safe journeys, while its clear blue color helped make it a popular gemstone for jewelry.
April Birthstone: Diamond
Diamond is the hardest naturally occurring mineral, ranking 10 on the Mohs scale. Although commonly associated with colorless stones, diamonds can occur in many colors, including yellow, brown, pink, blue, and green.
| Mohs Hardness | 10 |
|---|---|
| Toughness | Fair |
| Common Colors | Colorless, yellow, brown, pink, blue, and more |
Diamonds have been valued for centuries, first becoming especially important as gemstones in India before gaining popularity throughout Europe and eventually becoming one of the world's best-known jewelry gemstones.
Want to understand how diamonds are evaluated and selected? Explore our Diamond Buying Guide and Diamond Education Guide.
May Birthstone: Emerald
Emerald is the green variety of beryl. Its color can range from light green to deep, vivid green, and natural inclusions are common enough to have their own traditional name: jardin, French for “garden.”
| Mohs Hardness | 7.5–8 |
|---|---|
| Toughness | Poor to fair |
| Common Colors | Light to deep green |
Emerald has a long history of importance in jewelry and culture. Ancient Egyptians mined emeralds in the Eastern Desert, and the gemstone has been associated with fertility, renewal, and protection in different cultures.
Learn more about emerald symbolism in What Does Emerald Symbolize? or explore Where Are Emeralds Found?
June Birthstone: Pearl
Pearls are organic gems formed inside certain mollusks. Unlike most gemstones, which are minerals formed through geological processes, pearls develop through biological processes.
| Mohs Hardness | 2.5–4.5 |
|---|---|
| Toughness | Poor |
| Common Colors | White, cream, pink, gray, black, and more |
Pearls have been prized across cultures for thousands of years. Their natural luster and unusual origin made them symbols of beauty, wealth, purity, and status long before cultured pearls became widely available.
Explore pearl varieties and terminology in All About Pearls: Types & Terminology, or learn about their symbolism in What Do Pearls Symbolize?
June Birthstone: Moonstone
Moonstone is known for its soft, floating glow called adularescence. As light moves across the stone, the effect can appear to shift beneath the surface, giving moonstone its distinctive appearance.
| Mohs Hardness | About 6–6.5 |
|---|---|
| Toughness | Fair |
| Common Colors | Colorless, white, gray, peach, pink, green, and brown |
Moonstone has been associated with the moon in many traditions because of its changing, luminous appearance. It has been used in jewelry for generations and became especially popular during the Art Nouveau period.
June Birthstone: Alexandrite
Alexandrite is a rare variety of chrysoberyl famous for its color-changing effect. In daylight it can appear green or bluish-green, while incandescent light can bring out reddish or purplish tones.
| Mohs Hardness | 8.5 |
|---|---|
| Toughness | Good |
| Common Colors | Green, bluish-green, red, purple-red |
Alexandrite was discovered in Russia in the 19th century and became associated with the Russian imperial family. Its rarity and dramatic color change have made it one of the most distinctive gemstones in the chrysoberyl family.
July Birthstone: Ruby
Ruby is the red variety of the mineral corundum. Its color ranges from pinkish-red to deep red, with vivid red stones traditionally considered especially desirable.
| Mohs Hardness | 9 |
|---|---|
| Toughness | Good |
| Common Colors | Red to pinkish-red |
Ruby has been prized for centuries and has been associated with passion, power, protection, and prosperity in different cultures. Fine rubies are also among the most valuable colored gemstones.
August Birthstone: Peridot
Peridot is the gem variety of olivine and is known for its distinctive yellow-green to olive-green color. Unlike many gemstones, its color is caused primarily by its chemical composition rather than trace impurities.
| Mohs Hardness | 6.5–7 |
|---|---|
| Toughness | Fair |
| Common Colors | Yellow-green to olive |
Peridot has been used as a gemstone for thousands of years. Ancient sources sometimes referred to stones now believed to be peridot as “emerald,” and the gem has a long association with protection and light.
August Birthstone: Spinel
Spinel occurs in a wide range of colors, including red, pink, blue, orange, purple, and black. Red spinel was historically mistaken for ruby in some famous jewels because the two gemstones can look remarkably similar.
| Mohs Hardness | 8 |
|---|---|
| Toughness | Good |
| Common Colors | Red, pink, blue, orange, purple, black |
Spinel has a long jewelry history, but it was often overlooked because red spinel was confused with ruby. Modern gemology has established spinel as a distinct gemstone with its own characteristics and appeal.
September Birthstone: Sapphire
Sapphire is the gem variety of corundum in every color except red, which is classified as ruby. Although blue is the most familiar sapphire color, pink, yellow, green, and other colors are also found.
| Mohs Hardness | 9 |
|---|---|
| Toughness | Good |
| Common Colors | Blue, pink, yellow, green, purple, and more |
Sapphires have been associated with royalty, wisdom, and protection in many historical traditions. Their hardness and broad color range also make them practical choices for many types of jewelry.
October Birthstone: Opal
Opal is famous for its play-of-color, an optical effect that can display flashes of multiple colors as the stone moves in the light. Opals can also occur without play-of-color.
| Mohs Hardness | 5.5–6.5 |
|---|---|
| Toughness | Poor |
| Common Colors | White, black, gray, multicolored |
Opal has been admired since antiquity for its unusual flashes of color. Different cultures have attached a wide range of meanings and symbolism to the gemstone.
Learn more in All About Opals: Your Gemstone Guide.
October Birthstone: Tourmaline
Tourmaline is one of the most colorful gemstone families. It occurs in many colors, and individual crystals can sometimes show more than one color. Green, pink, red, blue, and watermelon tourmaline are among the best-known varieties.
| Mohs Hardness | 7–7.5 |
|---|---|
| Toughness | Fair to good |
| Common Colors | Pink, red, green, blue, black, multicolored |
Tourmaline became particularly popular as a jewelry gemstone in the 19th and 20th centuries. Its exceptional range of colors makes it especially interesting to collectors and jewelry designers.
November Birthstone: Citrine
Citrine is the yellow to orange-brown variety of quartz. Its warm colors range from pale yellow to rich golden orange, making it a distinctive and approachable colored gemstone.
| Mohs Hardness | 7 |
|---|---|
| Toughness | Good |
| Common Colors | Yellow to orange-brown |
Citrine has been associated with warmth, prosperity, and abundance in different historical traditions. These historical associations help explain some of the symbolism that has surrounded citrine over time. Today, citrine is valued for its warm color, natural beauty, and place among November birthstones.
December Birthstone: Blue Topaz
Topaz occurs naturally in several colors, but blue topaz is especially popular in jewelry. Its blue color ranges from light sky blue to deeper shades.
| Mohs Hardness | 8 |
|---|---|
| Toughness | Good |
| Common Colors | Light to medium blue |
Blue topaz became widely available as a jewelry gemstone after methods for creating its blue color were developed. Its hardness, clarity, and range of blue shades have made it a popular choice for December jewelry.
December Birthstone: Turquoise
Turquoise is an opaque gemstone known for its blue to blue-green color. Matrix, the natural host rock that can remain visible in turquoise, can create distinctive patterns across the surface.
| Mohs Hardness | 5–6 |
|---|---|
| Toughness | Fair |
| Common Colors | Blue, blue-green, green |
Turquoise has been used in jewelry and decorative objects for thousands of years. It has held particular cultural importance in several regions, including ancient Egypt, Persia, and the Indigenous cultures of North America.
December Birthstone: Tanzanite
Tanzanite is a blue to violet variety of the mineral zoisite found in Tanzania. Its color can shift between blue, violet, and burgundy tones depending on the lighting and viewing direction.
| Mohs Hardness | 6–7 |
|---|---|
| Toughness | Fair |
| Common Colors | Blue, violet, blue-violet |
Tanzanite was discovered in Tanzania in the 20th century and quickly became known for its unusual blue-violet color. Its geographic source is unusually limited compared with many other gemstones.
Additional Gemstones & Materials
Amber
Amber is fossilized tree resin rather than a mineral gemstone. It can range from nearly transparent golden yellow to orange, brown, red, and even unusual green or blue varieties.
| Mohs Hardness | About 2–2.5 |
|---|---|
| Toughness | Fair to poor |
| Common Colors | Yellow, golden, orange, brown, red, and more |
Some amber contains preserved insects, plant material, or other inclusions. These natural inclusions can make individual pieces especially interesting.
SHOP AMBER JEWELRYBlack Onyx
Black onyx is a variety of chalcedony, a form of quartz. Although onyx occurs naturally in several colors and patterns, uniformly black material is especially familiar in jewelry.
| Mohs Hardness | About 6.5–7 |
|---|---|
| Toughness | Good |
| Common Colors | Black, with banded varieties also occurring naturally |
Black onyx has long been used for rings, pendants, earrings, cuff links, and other jewelry because of its smooth surface and dramatic dark color.
SHOP BLACK ONYX JEWELRYCameo & Shell
Cameo jewelry features a raised image or design carved into a material with contrasting layers. Shell is one of the materials traditionally used for cameos, although cameos can also be carved from gemstones, coral, lava, and other materials.
| Material | Often shell, but also gemstone and other materials |
|---|---|
| Hardness | Varies by material |
| Common Colors | Often cream, white, pink, brown, or contrasting layered colors |
Cameos have a long history in European jewelry and became especially popular during the Victorian era. The carved designs often depict portraits, figures, mythological subjects, or decorative motifs.
Learn more about the history and characteristics of these pieces in What Is Cameo Jewelry?
Coral
Gem-quality coral is an organic material formed by colonies of marine organisms. Red and pink coral have been used in jewelry for centuries, while other colors also occur.
| Mohs Hardness | About 3–4 |
|---|---|
| Toughness | Fair |
| Common Colors | Red, orange, pink, white, black |
Because coral is relatively soft and porous, it needs more careful handling than many mineral gemstones. Prolonged exposure to chemicals, heat, and harsh cleaning methods can damage it.
SHOP CORAL JEWELRYJade
Jade refers to two different minerals: jadeite and nephrite. Both are valued for their toughness, smooth appearance, and long cultural history. Jade can occur in several colors, although green is particularly famous.
| Mohs Hardness | About 6–7 |
|---|---|
| Toughness | Excellent |
| Common Colors | Green, white, lavender, yellow, brown, black |
Jade has been especially important in Chinese, Mesoamerican, and other cultural traditions. Its exceptional toughness helped make it useful not only for jewelry and ornaments but also for tools and ceremonial objects.
SHOP JADE JEWELRYLabradorite
Labradorite is a feldspar mineral known for labradorescence, an optical effect that can produce flashes of blue, green, gold, or other colors across a gray to dark body.
| Mohs Hardness | 6–6.5 |
|---|---|
| Toughness | Fair |
| Common Colors | Gray, blue, green, gold, multicolored |
The shifting flashes are caused by light interacting with structures within the feldspar. Each piece can therefore have a different pattern and intensity of color.
SHOP LABRADORITE JEWELRYLapis Lazuli
Lapis lazuli is an opaque blue rock composed primarily of the mineral lazurite along with other minerals. Small flecks of pyrite can create its characteristic golden sparkle.
| Mohs Hardness | About 5–5.5 |
|---|---|
| Toughness | Fair |
| Common Colors | Deep blue, blue-violet, with possible white or gold inclusions |
Lapis lazuli has been prized for thousands of years. Ancient civilizations used it for jewelry, carvings, and pigments, and material from Afghanistan has been especially important throughout its history.
SHOP LAPIS LAZULI JEWELRYMalachite
Malachite is an opaque green copper carbonate mineral recognized by its distinctive bands and concentric patterns. Shades can range from pale green to deep forest green.
| Mohs Hardness | 3.5–4 |
|---|---|
| Toughness | Poor to fair |
| Common Colors | Light to deep green |
Malachite has been used for jewelry, carvings, decorative objects, and pigments for thousands of years. Its dramatic natural patterning means that no two pieces have exactly the same appearance.
SHOP MALACHITE JEWELRYMother of Pearl
Mother of pearl, also called nacre, is the iridescent material that lines the inside of certain mollusk shells. Its layered structure produces a soft, shimmering appearance.
| Mohs Hardness | About 2.5–4.5 |
|---|---|
| Toughness | Poor |
| Common Colors | White, cream, pink, gray, and iridescent shades |
Mother of pearl has been used for jewelry, buttons, decorative objects, and inlays for centuries. Its iridescence comes from the way light interacts with the microscopic layers of nacre.
SHOP MOTHER OF PEARL JEWELRYQuartz
Quartz is one of the most common minerals on Earth and occurs in a remarkable range of colors and varieties. Amethyst and citrine are well-known quartz varieties, while smoky quartz gets its brown to gray color from natural irradiation and other factors.
| Mohs Hardness | 7 |
|---|---|
| Toughness | Generally good |
| Common Colors | Colorless, purple, yellow, brown, pink, green, gray, and more |
Quartz is especially interesting because relatively small differences in composition and natural conditions can produce very different appearances. Varieties used in jewelry include amethyst, citrine, rose quartz, smoky quartz, and many others.
SHOP QUARTZ JEWELRYGemstone Jewelry Care
Gemstone jewelry should be cared for according to the characteristics of the individual stone. Softer or more fragile materials, such as pearl, opal, coral, amber, and mother of pearl, require more protection from scratches, chemicals, heat, and impact than harder gemstones.
Learn more about cleaning, storage, and everyday wear in our Ultimate Guide to Gemstone Jewelry Care.
Explore Gemstone Jewelry
From traditional birthstones to unusual colored gems and vintage materials, gemstone jewelry offers an incredible range of color, history, and character.
EXPLORE GEMSTONE JEWELRY