Gemstone

Several terms can refer to the same idea. For other uses, see Gemstone (disambiguation), Gems (disambiguation), Gem (disambiguation), Jewels (disambiguation) and Precious stone (disambiguation).

A gemstone (also called a fine gem, jewel, precious stone, semiprecious stone, or simply gem) is a piece of mineral crystal which, when cut or polished, is used to make jewelry or other adornments. Certain rocks (such as lapis lazuli, opal, and obsidian) and occasionally organic materials that are not minerals (such as amber, jet, and pearl) may also be used for jewelry and are therefore often considered to be gemstones as well.

Most gemstones are hard, but some softer minerals such as brazilianite may be used in jewelry because of their color, luster, or other physical properties that have aesthetic value. However, generally speaking, soft minerals are not typically used as gemstones by virtue of their brittleness and lack of durability.

Found all over the world, the industry of coloured gemstones (i.e. anything other than diamonds) is currently estimated at US$1.55 billion as of 2023 and is projected to steadily increase to a value of $4.46 billion by 2033.

A gem expert is a gemologist, a gem maker is called a lapidarist or gemcutter, and a diamond cutter is called a diamantaire.

Characteristics and classification

Long ago, people in ancient Greece started sorting special stones into two groups: precious and semi-precious. Today, the precious stones are emerald, ruby, sapphire, and diamond. All other gemstones are called semi-precious. These precious stones are very rare and very hard, scoring between 8 and 10 on a scale that measures hardness. Gemologists, who are experts in studying gems, look at many things to identify a gemstone. They check what the gem is made of, like carbon for diamonds or aluminium oxide for sapphires and rubies. They also study the shape and form of the gem, such as whether it is cubic or trigonal.

Gemstones can be grouped into different types based on their color, how they shine, and how hard they are. For example, ruby is a red type of corundum, while any other color of corundum is called sapphire. Other examples include different colors of beryl, such as green emerald, blue aquamarine, and pink morganite. Experts also look at a gem’s brightness, how it bends light, and any tiny flaws inside it to describe and value the gemstone.

Value

Gemstones do not have a single way to decide their value. For diamonds, a special system was made by the Gemological Institute of America in the 1950s. Before that, people used to look at gemstones with just their eyes. This new system added a special look using a magnifying glass to check how clear the diamond is.

There is a helpful way to remember the main things that decide a diamond’s value, called the “four Cs”: color, cut, clarity, and carats. These ideas can also help us think about other gemstones. For diamonds, how well they are cut is very important, followed by how clear they are and their color. A well-cut diamond will sparkle and show beautiful colors.

For colored gemstones, the beauty and purity of their color are very important. Other things like how clear they are, special patterns inside the stone, and rare effects also add to their value.

Besides common gems like diamonds, rubies, sapphires, and emeralds, pearls and opal are also considered very special. In the past, amethyst was also thought to be very valuable, especially in ancient Greece. Even today, stones like aquamarine, peridot, and cat’s eye are popular and valued.

Now, many gemstones are used in fancy jewelry, and their value can change based on fashion, how rare they are, and other factors. But diamonds, rubies, sapphires, and emeralds are still known as some of the most prized gems.

Some very rare gemstones, known mostly to experts, include andalusite, axinite, cassiterite, clinohumite, painite, and red beryl.

The price of a gemstone depends on its clarity, how rare it is, how beautiful it looks, and how much people want it. Colored stones’ prices change with supply and demand, while diamond prices are decided in more complex ways.

Besides being used in jewelry, some people believe that gemstones have special powers to help with healing.

Grading

Some special places, called laboratories, check and give reports about gemstones. These laboratories help people understand more about the gems.

Here are some of the well-known laboratories:

• Gemological Institute of America (GIA), which teaches about gems and gives reports on diamonds
• International Gemological Institute (IGI), which checks diamonds, jewelry, and colored stones
• Hoge Raad Voor Diamant (HRD Antwerp) in Belgium, one of Europe’s oldest laboratories
• American Gemological Society (AGS), which is not as old as GIA
• Asian Institute of Gemological Sciences (AIGS) in South East Asia, the oldest institute there for gem research
• Swiss Gemmological Institute (SSEF), started by Henry Hänni, which focuses on colored gemstones and pearls
• Gübelin Gem Lab, a traditional Swiss lab started by Eduard Gübelin

Each laboratory has its own way of checking gemstones. Sometimes one lab might call a stone “pink” while another calls it something else. To make things more consistent, several top laboratories work together in a group to standardize their reports and methods.

Cutting and polishing

Some gemstones are used just as they are found in nature. But most are cut and polished to make beautiful jewelry. There are two main ways to do this:

• Stones are cut into smooth, dome-shaped pieces called cabochons. This shape has been popular for a very long time and is stronger than other shapes.
• Stones are cut using a special machine called a faceting machine to make many small flat surfaces called facets.

Opaque or semi-opaque stones like opal, turquoise, and variscite are usually made into cabochons. This shows off the stone's color and shine best. Tools are used to shape and polish these smooth domes.

Clear gems are usually faceted. This means cutting many flat surfaces to show the stone's inner beauty. Light reflects off these surfaces, making the gem sparkle. The angles for these surfaces depend on the stone’s optical properties. If the angles are not just right, the light will pass through instead of sparkling back to the viewer. A faceting machine holds the stone steady while cutters shape and polish each flat surface. Sometimes special curved tools are used for curved surfaces.

Colors

The color of any material depends on how light behaves. Daylight, which we often call white light, contains all the colors of the rainbow mixed together. When this light hits a material, most of it gets absorbed, but a small amount of a specific color is reflected. This reflected color is what our eyes see.

Even materials that are mostly the same can show different colors. For example, ruby and sapphire are made of the same thing (corundum) but look different because of tiny amounts of other elements. These elements change which colors are absorbed and which are reflected. Sapphires can be many shades of blue or pink, and some special ones, called "padparadscha sapphire", have unusual colors from yellow to orange-pink.

These color changes happen because of the stone’s atomic structure. Sometimes, just one atom in a million is different, and this can change the color. For example, beryl is usually clear, but with chromium it becomes green emerald, and with manganese it turns pink morganite. Different treatments can also change a gem’s color by adjusting these tiny differences.

Treatment

Gemstones are often treated to make their color or clarity better. These treatments can also help make the stone last longer. Besides cutting and polishing, there are other ways to improve how a gemstone looks. Depending on the treatment, it can change the value of the stone. Some treatments are widely used because they make stable gems, while others are less common because the color might change back over time.

Long ago, people used simple methods to treat gemstones. For example, they used metal foil to improve a gemstone’s color. Other old methods include using oil or dyes, as written about 2000 years ago.

Heat is another way to treat gemstones. It can make colors better or worse. For example, heating amethyst can turn it into citrine. Aquamarine is often heated to make it a clearer blue. Most tanzanite is heated to remove brown tones and make it a more desirable blue or purple. Sapphires and rubies are also often heated to improve their color and clarity.

Radiation is used in the jewelry industry to create colors that are rare in nature. This process can make gemstones radioactive, so there are rules to keep people safe. For example, most blue topaz and green quartz are treated this way to change their color. Diamonds can also be treated to become blue-green or green.

Some gemstones like emeralds and turquoise are treated with wax or oil to fill in cracks and make them look clearer. This helps hide natural flaws and improve the appearance.

Fracture filling is used for gemstones like diamonds, emeralds, and sapphires. In 2006, rubies with large cracks were filled with glass to make them look better.

Bleaching is another common treatment. It uses chemicals to reduce a gemstone’s color. After bleaching, the stone can be dyed to give it a new color. Hydrogen peroxide is often used for this, especially for jade and pearls. Bleaching can also be followed by impregnation to make the gemstone more durable.

Socioeconomic issues in the gemstone industry

The gemstone industry can greatly affect the lives of people, especially in places where it provides important jobs. Changes in what people want to buy and how much they are willing to pay can change the lives of those who work in mining and selling gemstones.

Unfortunately, some mines, especially in poorer countries, have unsafe conditions, low pay, and difficult work for the people who work there. These workers often come from difficult backgrounds and face many hardships. Mining often happens in places far from cities, where there aren’t good schools or hospitals, making it hard for communities to grow and thrive.

Mining can also harm the environment, leading to problems like cutting down forests, soil losing its nutrients, and water becoming dirty. These changes can hurt animals and plants and make it harder for the industry to continue in a healthy way. To make things better, everyone involved—including governments, business leaders, and communities—needs to work together to create fairer and safer ways to mine and sell gemstones. This includes making rules to protect workers and the environment, and supporting local communities with better schools and healthcare.

Synthetic and artificial gemstones

Synthetic gems are made to look just like natural ones, but they are created in a lab. They have the same look, feel, and makeup as natural gems. Other stones, called imitation or simulated gems, look similar but are made from different materials like glass or plastic.

Some examples of simulated stones are cubic zirconia, synthetic moissanite, and synthetic corundum. These look like real gems but are not the same inside. Lab-created gems, however, are the same as natural ones. For example, lab-created diamonds, rubies, sapphires, and emeralds have the same properties as natural ones. They often have brighter colors because they don’t have natural impurities.

There are different ways to make synthetic gems. One common way is the flame fusion process, where special powders are melted to form crystals. Another way is the flux growth process, which uses a special liquid to grow the gems. The hydrothermal growth process copies how gems form in nature, using high pressure and temperature to create them. Each method leaves tiny clues that can help experts tell if a gem is natural or synthetic.

List of rare gemstones

Some gemstones are very rare and special. Painite was found in 1956 in Myanmar and was once thought to be the rarest mineral on Earth. Tanzanite, discovered in 1967 in Tanzania, might become even rarer than diamonds in the next few decades.

Other rare gemstones include Hibonite from Madagascar, Red beryl from Utah, and Black opal from Australia. Each of these gemstones has unique qualities that make them special and hard to find.

In popular culture

French singer Nolwenn Leroy was inspired by gemstones for her 2017 album Gemme, which means gemstone in French, and for a single song with the same name.

The Japanese manga and anime series Land of the Lustrous features characters that look like human beings but are really jewels.

The American animated TV series Steven Universe has characters who are magical gemstones that appear as human females.