Gemstone Encyclopedia

Education

Gemstone Encyclopedia

Get to know your gemstones. We organize our most commonly chosen gems with their care, history, and notable qualities.

Gold and emerald necklace, Roman, 1st–2nd century CE.

Emerald

MOHS HARDNESS: 7.5 - 8

Emerald is a vibrant green beryl and a favorite of Cleopatra's. Expect to see inclusions that dealers like to call an internal “jardin,” or garden. Due to the crystal shape emeralds are commonly cut as rectangular step cuts called emerald cuts.

Be extra gentle with your emerald jewelry. Light, chemicals, heat, and steam can all damage the stone. Clean with soap and water only.

GIA's Emerald Care Guide

Lighter, Pierre Schlumberger, 1939

Ruby

MOHS HARDNESS: 9

Rubies get their characteristic fire from the presence of chromium. A stone full of life and sensuality.

Corundum (ruby and sapphire) is relatively hard—9 on the Mohs scale. It is an excellent choice for rings and other jewelry subject to daily wear.

GIA's Ruby Care Guide

Necklace with cameo of Veronica's Veil, Firm of Castellani, ca. 1870

Sapphire

MOHS HARDNESS: 9

Sapphires have captivated mystics, royalty, and jewelers for millennia, symbolizing wisdom and nobility. As a variety of the corundum mineral, they are prized for their brilliant color and exceptional durability. They come in all colors.

Corundum (ruby and sapphire) is relatively hard—9 on the Mohs scale. This makes it a great choice for rings and other mountings subject to daily wear.

GIA's Sapphire Care Guide

Detail: Portrait of a Lady in Allegorical Guise by Pierre Mignard, 17th century

Pearl

MOHS HARDNESS: 2.5 - 3

"The world's oldest gemstone." Pearls are formed within the soft tissue of certain mollusks, with the rarest and most treasured being natural pearls that occur spontaneously in the wild. They can also be cultured.

Throughout history, they have inspired countless origin myths: said to be the tears of gods, droplets from the heavens, or lightning captured within an oyster shell. These legends imbued pearls with a mystical vitality, enhancing their allure.

GIA's Pearl Care Guide

The 9 large diamonds cleaved from the Cullinan Diamond. Royal Collection Trust.

Diamond

MOHS HARDNESS: 10

The hardest gem of all is made of just one element: carbon. Diamonds are 8 times harder than anything else in nature. They are valued based on their colorless nature and purity. Most natural diamonds are primeval.

Diamonds play a past and present role in social, economic, and environmental dynamics, with many consumers opting to source recycled or lab grown diamonds. We source our new natural diamonds as ethically as possible to align with our values. We are happy to share more information as needed to support your decision making process.

Diamond Grading Explained

GIA Diamond Care Guide

Opal

MOHS HARDNESS: 5 - 6.5

Because opal has the colors of other gems, the Romans thought it was the most precious and powerful of all. They named it opalus, meaning "precious stone." Many cultures have credited opal with supernatural origins and powers. Arabic legends say it falls from the heavens in flashes of lightning. The ancient Greeks believed opals gave their owners the gift of prophecy and guarded them from disease. Europeans have long considered the gem a symbol of hope, purity, and truth.

GIA's Guide to Evaluating Opals

GIA's Opal Care Guide

Oval gem with Kassandra kneeling at the Palladion, Greek, Late Hellenistic Period. late 1st century B.C.

Aquamarine

MOHS HARDNESS: 7.5 - 8

Named after seawater, aquamarine’s fresh watery hue is a cool plunge into a refreshing pool. Aquamarine is the blue to slightly greenish-blue variety of the mineral beryl. It is a good choice for daily wear if you're cautious to protect it from hard knocks and things that would scratch the surface.

GIA's Aquamarine Care Guide

image by Jeff Scovil.

Tourmaline

MOHS HARDNESS:

Its name is derived from the Sinhalese tōramalli.

Brightly colored Ceylonese gem tourmalines were brought to Europe in great quantities by the Dutch East India Company to satisfy a demand for curiosities and gems. Tourmaline comes in a range of colors from dark green to pinkish purple and has one of the widest color ranges of any gem.

GIA's Tourmaline Care Guide

Garnet ring stone, Signed by Apollonios, ca. 1st century BCE

Garnet

MOHS HARDNESS: 6.5 - 7.5

Garnet refers to a group of gemstones treasured in jewelry since the Bronze Age. Their name derives from the Latin granatus, inspired by their resemblance to pomegranate seeds.

Garnets have been among the most popular gemstones in jewelry throughout history. They have fair to good toughness, making them durable enough for all jewelry styles as long as they are treated with the proper care. Garnets should not be subjected to any hard blows or rough wear.

GIA's Garnet Care Guide

Stamp seal, Iran or Mesopotamia ca. 3rd-7th century CE

Onyx

MOHS HARDNESS: 7

Onyx, derived from the Greek word "onux" meaning "claw," has a rich history spanning millennia, used in jewelry, carvings, and decorative arts. It was believed to ward off negative energy, provide inner harmony, and symbolize rebirth or new beginnings.

Onyx is a type of chalcedony and is sometimes considered a type of agate. Since onyx often receives dye treatments, proper care is essential. Clean it only with a soft brush, mild detergent, and warm water. Avoid using ultrasonic or steam cleaners.

Peridot ring stone featuring Apollo, Roman, 1st century BCE–2nd century CE

Peridot

MOHS HARDNESS: 6.5 - 7

The gem variety of the mineral Olivine. Peridot was first mined exclusively on Topazios Island in the Red Sea as early as 300 BCE. Revered by the Egyptians as the "gem of the sun," it was believed to hold protective powers when set in gold as a talisman. Also known as the "Evening Emerald" in ancient times, the finest peridots display a radiant green with a subtle golden undertone, these lush hues embody peridot’s true splendor.

GIA'S Peridot Care Guide

Plaque with Harpokrates (or similar) on a lotus, Ptah and Re-Harakhty. 332–30 B.C. Egypt.

Lapis Lazuli

Originating from the Persian word for the gem, lāžward, lapis lazuli is a rock composed primarily of the minerals lazurite, pyrite, and calcite. Lapis Lazuli artifacts date back to 7570 BC. The stone is ground into powder for ultramarine pigment.

Warm, soapy water is the safest way to clean lapis lazuli. It’s best to test a small, inconspicuous area first, because some dye treatments are not stable.

GIA's Lapis Care Guide

Pair of Earflare Frontals, Maya, 3rd–6th century © The Met Collection

Jadeite

MOHS HARDNESS: 6.5 - 7

Jade was considered the most precious of all materials in the ancient Maya world. Its vibrant green hue was compared to other revered natural wonders, such as ripening crops and the iridescent feathers of the quetzal bird. The stone’s ability to endure, unchanged, for centuries symbolized timelessness, permanence, and longevity. When polished, jade achieves a high, glossy shine, as if it has been dipped in water. It remains cool to the touch but quickly absorbs the warmth of a human hand. This unique quality led the Maya to view jade as a living, breathing, and soulful substance.

GIA's Jade Care Guide

Abalone

MOHS HARDNESS: 3 - 4

Abalone refers to several species of mollusk, known for their vibrant, iridescent shells. These creatures have been a vital food source for over 12,000 years and are highly valued for their striking purple and green nacre. The unique beauty of abalone shell has long been used in jewelry, buttons, and as inlays in musical instruments and furniture, adding a touch of natural elegance and color.

AAbalone can be damaged by chemicals and even prolonged exposure to sunlight.

Detail: Monna Vanna, Dante Gabriel Rossetti, 1866

Coral

MOHS HARDNESS: 3 - 4

Coral has been cherished in jewelry for over 30,000 years. In Greek mythology, red coral was believed to be the petrified blood of Medusa, spreading into the sea after her death at the hands of Perseus. In Ancient Rome, it was used as a protective talisman against the evil eye, especially for children, and continues to be worn today as a symbol of luck.

All of our coral is repurposed from vintage jewelry, giving it new life and meaning. Coral is porous, so avoid chlorinated pools, heat, perfume, cosmetics, and other chemicals. Do not clean with a steam or ultrasonic cleaner.
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