Gemstone Buying Guide

Gemstone Buying Guide

Tips for selecting the right gemstone

April 1, 2016

by Katie Dudley Gemstone Specialist

This gemstone buying guide will help you select quality gemstones, whether you're expanding your personal jewelry collection or giving a gift to someone you care about.

What Makes a Gemstone

Pink, green, blue, and purple gemstone rings on a white background.

A gemstone is a mineral or other organic material that has been cut, and polished. When certain minerals, stones, and pearls are cut, polished, and shaped, those materials become gems. It's only when gemstones are placed in a jewelry settings that they become jewels. There is no actual scientific or geological definition for a gemstone, gem, or jewel. Gemstones are minerals that are mined from the Earth and sea. Most gems form in the Earth's crust, approximately three to 25 miles beneath the Earth's surface. The two gemstones that are found at deeper depths are diamonds and peridot.

Oyster shell with a white pearl on a white background.

Organic Gemstones

Most gemstones are mined from the Earth; however, some items classified as gems come from organic materials instead. This means they come from a living organism like plants and animals. There aren't a wide variety of organic gemstones, but the most popular are pearl, bone, amber, coral, and jet.

White pearl necklace on a white background.


Pearls are unique in the fact that they don't require any processing; they naturally display a pearly luster. Oysters produce pearls in both saltwater and freshwater environments. These organic gems have been used for more than 6,000 years as an embellishment.

Amber ring with silver band on a white background.


Amber is formed from the hardened resin of ancient pine trees. Fragments of wood, insects, spiders, and other small organisms have been preserved beautifully in the resin and are often featured in the finished product.

Coral stem on a white background.


Coral is a skeletal structure built by small ocean animals called coral polyps. When the coral polyps die, the hardened skeleton remains, and this is the material that is used as a gemstone. Coral naturally comes in a variety of colors, including orange, pink, red, white, gray, and black.

Jet bead necklace on a white background.


Jet is composed of polished bituminous coal. In the 19th century, jet was often worn as mourning jewelry because of its dark color and simple appearance. Today jet as a material is rarely used. It has been replaced by look-alikes and imitations. Substitutes for jet are regularly marketed as "jet black" in color.

Mixed colored precious gemstones on a white background.

Precious and Semiprecious

Since the mid 1800's, gemstones have been categorized into precious and semi-precious stones. The term precious stone was primarily used for gems like diamonds, rubies, sapphires, and emeralds. All other gems were categorized as semi-precious. The perception of value based on these classifications can be misleading, but many semi-precious stones are far more valuable than some precious stones.

Mixed colored semiprecious gemstones on a white background.

Semi-precious gemstones include, but aren't limited to, agate, amber, amethyst, aquamarine, aventurine, chalcedony, chrysocolla, chrysoprase, citrine, garnet, hematite, jade, jasper, jet, kunzite, lapis lazuli, malachite, moonstone, obsidian, onyx, peridot, rhodonite, sunstone, tiger's eye, tanzanite, topaz, turquoise, and tourmaline.

Natural untreated aquamarine  gemstone held between tweezers on a white background. Aquamarine gemstone silver ring on a white background.


The treatment and enhancement of gemstones have been around for hundreds of years. Some enhancements are simple while others provide a drastic change in the gem itself. For example, when aquamarine is properly heated, it will lose it's green tint and become a pure blue. Another example is ruby. This stone is commonly heat-treated. It is heated to almost melting, creating a new crystal structure and allowing a richer red hue. Enhancements can be cosmetic, improving clarity, color, or brilliance, and some stabilize the gem's chemical composition. An estimated 80 percent of gemstones have been treated in some way before reaching the retailer.

Some gems wouldn't exist if it weren't for treatments. Heating is the most common treatment available. It causes the color of a stone to lighten, darken, or change completely. It can also improve a stone's clarity and brightness. For example, citrine is a yellow variety of the mineral quartz. It's made, by using a heat treatment on a purple amethyst, which transforms the gem into shades of yellow, gold, and orange. If it weren't for the ease of treating this stone, citrine would be much more expensive. The following gems are routinely heat-treated: tanzanite, citrine, pink topaz, aquamarine, tourmaline, ruby, sapphire, and zircon.

Every piece of gemstone jewelry on will have a gemstone treatment code listed. We've added a list of treatment codes below so you can become familiar with the terms and make a more informed jewelry purchase.

Gemstone Treatment Codes

Treatment Code N: The “N” symbol is used when natural stones are not currently enhanced by any method.

Treatment Code E: The “E” symbol indicates the gemstone has probably undergone a traditional enhancement procedure.

Other Treatment Codes: Used when definite information on standard treatments is not known or when the "N" and "E" codes don't apply.

Enhancement Codes

Everything you need to know about gemstone enhancement codes right at your fingertips! This comprehensive list will give you the information you need to know about gemstone treatment codes when you're shopping for gemstone jewelry.

Enhancement Code Infographic
  • B Bleaching: The use of heat, light, and/or chemicals to lighten or remove a gemstone's color.
  • C Coating: The use of such surface enhancements like lacquering, enameling, inking, foiling, or sputtering of films to improve appearance, provide color, or add other special effects.
  • CR: This designation is used for any stone that is synthetic or laboratory created.
  • DBL Doublet: Jewelers make a doublet by gluing a thin layer of natural stone to a backing material. The backing material is used to thicken and give strength to the stone.
  • D Dyeing: The introduction of coloring matter into a gem to give it a new color or greater intensity.
  • DS Diffusion Treatment: Exposing the surface of a stone to chemicals combined with high heat. This treatment typically only changes the surface, so the inside of the stone would be a different color. This method is used to change the color of ruby, green topaz , and blue sapphire. Until treatments are perfected to the point where the entire stone can be changed, reputable dealers will always tell you which stones have been treated with this method. This practice is more generally accepted for star sapphires, as this will increase the star effect.
  • F Filling: The incorporation of colorless borax or other substances into the cracks that are a by-product of heating the stone. It is used only if a crack is visible at 10 times magnification.
  • G Gamma: Otherwise known as electron irradiation, gamma changes a gemstone's color. Irradiation may be followed by a heating process to stabilize the color.
  • H Heating: The use of high heat to alter the color, clarity, and/or phenomena of a gemstone.
  • HTHP High Temperature/High Pressure: The use of heat and pressure combined to create desired alterations of color, clarity, and/or phenomena.
  • I Impregnation: Introducing a colorless agent — usually plastic — into a porous gemstone to improve durability and appearance.
  • L Lasering: The use of a laser to drill into a diamond to remove or alter an inclusion.
  • O Oiling: Also known as resin infusion, oiling fills surface-breaking cavities and cracks with a colorless oil, wax, resin, or other colorless substances to improve the gemstone's appearance.
  • D Dyeing: The introduction of coloring matter into a gem to give it a new color or greater intensity.
  • R Irradiation: The use of neutrons, gamma, ultra-violet, and/or electron bombardment to alter a gemstone's color. Irradiation may be followed by a heating process.
  • S Bonding: The intentional use of a colorless agent, usually plastic, within a porous gemstone.
  • TA: Type A jade is a natural jade enhanced only with wax.
  • TB: Type B jade is a natural jade that is bleached in acid to remove undesirable staining, and then impregnated with wax or polymers.
  • TC: Type C jade is a natural jade that is dyed and sometimes bleached and impregnated with wax or polymers.
  • TPL Triplet: A triplet is a doublet that has a clear protective layer on top of the stone. The top layer may consist of clear quartz, glass, or hard plastic. This layer thickens and gives additional strength to the stone.
  • W Waxing/Oiling: The impregnation of colorless wax, oil, or paraffin into porous opaque gems to improve appearance.

How to Buy a Gemstone

Rarity, durability, beauty, size, and color all contribute to the price of the gemstone. Ultimately, the value of any gem is mostly determined by its beauty, size, cut, and popularity.

Circle diamond gold ring on a branch with green leaves.


Gemstones come in nearly every color on the spectrum. In fact, one gem variety can have many different hues. For example, sapphires, tourmaline, and garnets all come in blue, pink, and yellow.

When it comes to buying gems, color is the most important value factor. A color’s tone, saturation, and hue all factor into the price. The brighter, more vivid colors with a medium tone are the most valuable and sought-after stones.

  • Tone: Also known as value or lightness, tone refers to the lightness or darkness of color. Tones can range from clear to black.
  • Saturation: Also known as chroma or intensity, saturation refers to the amount of color present in the stone. A gemstone with excellent saturation reflects a pure color, without brown or grey hues.
  • Hue: There are six primary hues: violet, blue, green, yellow, orange, and red. Between the primary hues are secondary hues like blue-green. Gemstones that have pure primary colors are the most valuable. Gems that are very pale, very dark, or are tinged with brown or grey are less valuable.

Color preference is very personal. Just because a gem is the “perfect” color by industry standards, it doesn’t mean it’s the most eye-catching stone to you.


Because of the way gemstones form in the earth, many stones naturally have inclusions. The more valuable gems are those with either few inclusions or inclusions that are not visible to the naked eye.

Carat Weight & Rarity

Gemstones are sold by weight, not size. The weight measurement used is carat, which is one-fifth of a gram. Because each stone is made up of a different mineral, the density varies from stone to stone. For example, a one-carat emerald and a one-carat ruby will weigh the same, but the ruby will be smaller.

Some gems are rarely found in large sizes. This means you can expect to pay much more per carat for stones like ruby, sapphire, spinel, alexandrite, garnet, tsavorite, and emerald.


Different colors and cuts of gemstones in a row on a white background.

A special cut can bring out the brilliance and beauty of a gem, and each gemstone will handle light differently. There are a variety of options when it comes to your choice of cuts, but the style of cut you choose will depend on your own personal style.

Cushion-Cut Gemstone


Also known as "pillow-cut" gemstones, these are squares or rectangles with rounded corners.

Shop Cushion-Cut Gemstones ›
Emerald-Cut Gemstone


These are rectangles with step cuts on the sides and a large, flat top.

Shop Emerald-Cut Gemstones ›
Asscher-Cut Gemstone


These are rectangles with step cuts on the sides and a large, flat top.

Shop Asscher-Cut Gemstones ›
Heart-Cut Diamond


This romantic shape is the perfect symbol of love.

Shop Heart-Cut Gemstones ›
Marquise-Cut Diamond


This cut is like an oval but with pointed ends. Turned on its side, it looks like a woman's slightly parted lips.

Shop Marquise-Cut Gemstones ›
Oval-Cut Diamond


These rounded gemstones are longer than they are wide.

Shop Oval-Cut Gemstones
Pear-Cut Diamond


Also known as a "teardrop," these have one pointed end and one rounded end.

Shop Pear-Cut Gemstones ›
Princess-Cut Diamond


Traditionally squares but sometimes rectangles, princess-cut gemstones always have four pointed corners.

Shop Princess-Cut Gemstones ›
Radiant-Cut Diamond


These are squares or slight rectangles with four trimmed corners.

Shop Radiant-Cut Gemstones
Round-Cut Diamond


The most popular gemstone shape, round-cut gemstones are cut to have 58 facets.

Shop Round-Cut Gemstones ›
Baguette-Cut Diamond


Cut with 14 facets, these rectangular gemstones are traditionally used to accent other gemstones.

Shop Baguette-Cut Gemstones ›
Trillion-Cut Diamond


These are triangular gemstones with three equal sides that can be curved or straight.

Shop Trillion-Cut Gemstones

Gemstones for Every Occasion

When it comes to gift giving, the gifts that mean the most are the ones that offer something personal. You can do just that with gemstones. Each gem has its own history and mystical qualities that have long been believed to have symbolism as well as physical and emotional healing properties. Every time it is worn, fond memories will be recalled with a smile. Below are a few unique ideas sure to touch the hearts of those special people in your life.

A pearl gemstone ring in a burgundy box. Branches, metallic background.


Close up of a birthstone necklace pendant, Birthstone stackable ring and a ruby birthstone eternity bracelet on a white background.

Giving the gift of birthstone jewelry is personal and meaningful. Each gemstone correlates with a specific month. Birthstones have a rich history and add that sentimental touch to any gift. Visit our birthstone guide to learn more.

Zodiac Sign

Each of the signs of the zodiac rules a particular gemstone, also known as astral stones. The stones receive the vibrations of the matching astrological constellation, which helps strengthen your zodiac influence. Find your zodiac gemstone to enhance your own astrological energy.

Find your match and experience the potential benefits of increased awareness and growth.

Gemstones of the Zodiac Infographic
Dec 23rd - Jan 20th
Jan 21st - Feb 19th
Feb 20th - Mar 20th
Mar 21st - April 20th
April 21st - May 21st
May 22nd - June 21st
June 22nd - July 22nd
July 23rd - Aug 22nd
Aug 23rd - Sept 23rd
Sept 24th - Oct 23rd
Oct 24th - Nov 22nd
Nov 23rd - Dec 22nd
Blue Topaz


Close up of pink gemstone silver ring on a pink background.

Traditional diamond solitaire engagement rings aren't the only way to go when finding that perfect ring for that special someone. Colored gemstones like sapphires, emeralds, amethysts, and rubies can be more affordable and give a one-of-a-kind feel to any engagement ring setting.

Close up of a couple. Girl is wearing a blue gemstone ring.

Anniversary Stone

When shopping for your special anniversary, consider expressing your love and appreciation to your spouse, parents or relatives with a gemstone.

The traditional anniversary gift list has items such as paper, cotton and leather, why not add a little sparkle by celebrating your marriage with a gemstone. This Anniversary Gemstone Chart will help you choose the perfect stone for your special day.

Anniversary Gem Stone Guide Infographic

1st Anniversary
Traditional: Gold jewelry
Alternate: Peridot, Pearl

Shop all gold jewelry ›

2nd Anniversary
Traditional: Garnet
Alternate: Rose Quartz

Shop all garnet jewelry ›

3rd Anniversary
Traditional: Pearl
Alternate: Crystal, Jade

Shop all pearl jewelry ›

4th Anniversary
Traditional: Blue Topaz
Alternate: Blue Zircon

Shop all topaz jewelry ›

5th Anniversary
Traditional: Sapphire
Alternate: Blue Zircon

Shop all sapphire jewelry ›

6th Anniversary
Traditional: Amethyst
Alternate: Turquoise

Shop all amethyst jewelry ›

Just Because!

Different colors and cuts of pink gemstones and diamond rings resting on each other on a pink background.

Why wait for someone to give you the gift of gemstones? It's time to give yourself a gift to celebrate an achievement or simply treat yourself, just because! If you choose something you'll love and wear often, then you'll look and feel fantastic!

Caring For Your Gemstone Jewelry

A pearl ring and three diamond rings resting on a cloth. A bristle brush and white bowl and white flowers are in the background.

Cleaning Recommendations

Understanding how to care for your jewelry can make a big difference in preserving its beauty and shine; plus, it will also extend the life of your precious items.

Morning Routine: Put on jewelry after applying makeup, hairspray, perfumes, lotions, and any other cosmetics to reduce your gemstone's exposure to chemicals.

Daily Wear: Remove jewelry when performing tasks like working in the kitchen, gardening, cleaning chores, working on heavy equipment, or during exercise. This will prevent any physical damage and reduce the risk of exposing jewelry to chemicals and cleaning fluids. It's also a good idea to remove jewelry before entering the pool or spa. Chlorinated water can cause color changes and even structural damage.

Nightly Routine: Remove jewelry before bed and gently wipe items with a soft cloth to remove residues from the day. It is best to store jewelry in a case where items don't touch each other. This prevents the harder gemstones or other hard jewelry pieces from scratching softer ones.

Jewelry Storage: Proper jewelry storage is often overlooked. Avoid the temptation to toss jewelry into a drawer or on top of a dresser — that's a recipe for scratches and tarnishing. Jewelry should be stored away in a protective-lined jewelry box or a tarnish-resistant pouch. This protects items from sunlight and heat. Look for jewelry boxes that feature individual padded slots for rings, posts for earrings, and hooks for necklaces.

Gemstone Cleaning: Pour a small amount of dish soap (no detergents) into a bowl of lukewarm water. Use a small, soft brush to clean your jewelry, then lay items on a towel to dry. Avoid using ultrasonics, steamers, or intense heat when cleaning your jewelry at home.

Six-Month Cleaning: About every six months, take your jewelry to get professionally cleaned by a jeweler. Avoid December, which is usually the busiest time of the year for jewelers.

Yearly Security Check: Have your jewelry professionally examined to check the security of your precious stones and jewels. Here are a few questions you can ask the jeweler. Are the prongs holding your gemstones securely? Do your pearls need to be restrung? Does your ring need resizing? Is the clasp on your favorite necklace or bracelet still secure?

Gemstones by Color

Different colors of gemstones in a row on a white background.
  • PINK: pink tourmaline, pink spinel, pink smithsonite, rose quartz, pink topaz
  • RED: ruby, garnet, red spinel, rhodonite, coral, red onyx, red agate
  • YELLOW: gold citrine, yellow topaz, amber, citrine, yellow diamond
  • GREEN: emerald, peridot, jade, malachite, turquoise, chrysoprase
  • BLUE: sapphire, chalcedony, aquamarine, lapis lazull, blue topaz, blue opal
  • PURPLE: amethyst, purple jade, purple garnet, purple alexandrite, charoite, lolite
  • BLACK: tourmaline, black spinel, hematite, black sapphire, onyx, black diamond
  • Brown: smoky quartz, brown topaz, brown agate, tiger's eye, axinite
  • WHITE: diamond, opal, moonstone, pearl, white jade, white chalcedony

Gemstone Healing and Meanings

A person cupping their hands to hold several gemstones. A woman laying down with gemstones aligned to the chakras on her body .

Semiprecious and Precious Healing Stones

For some, gemstones aren’t just fashion accessories. Some people believe gemstones have healing metaphysical properties that add valuable improvements to your health, environment, and overall energy.

The healing power of gemstones is linked to chakras, which are energy centers within the human body that help regulate the body’s system and emotions. There are seven chakras within the body from the crown of your head to the base of your spine, and each are connected to the health of specific parts of your emotional and physical well being. The key to chakra healing is opening and balancing the chakras, which creates an overall harmonious flow of energy. There are many gemstones for each chakra that are said to aid in the healing and balancing process.

Diagram of the chakras in line with a silhouette of the body.


Strength & Courage
Healing: Heals emotional tension, stimulates the digestive system, strengthens the body, and heals skin disorders.
Chakras: Third Eye and Crown.

Shop all agate jewelry ›


Spirituality & Intuition
Healing: Calms the mind, reduces stress, eases headaches, helps with hormone production, strengthens the immune system.
Chakras: Third Eye and Crown.

Shop all amethyst jewelry ›


Healing: Harmonizes and heals the body. Releases stress and tension.
Chakras: Solar Plexus, Third Eye, and Crown.

Shop all ametrine jewelry ›


Clarity & Purification
Healing: Helps calm the nerves and relieve sore throats. Strengthens the liver, spleen, kidneys, and the pituitary and thyroid glands.
Chakras: All aligning, especially the throat.

Shop all aquamarine jewelry ›


Warm & Joyous
Healing: Sparks metabolism, improves quality of blood, and helps with circulation.
Chakras: Sacral, Solar Plexus, and Heart.

Shop all carnelian jewelry ›


Revitalizing & Cleansing
Healing: Balances hormones. Helps digestive organs, reduces infection, and detoxifies.
Chakras: Solar Plexus and Crown.

Shop all citrine jewelry ›

by Katie Dudley Gemstone Specialist

Katie isn't just a gemstone specialist, she's also a photographer and mother. In her free time, she enjoys exploring and taking pictures in the beautiful Utah mountains with her family.