Gemstones bring color, light and individual character to jewelry. Each gemstone has its own combination of color, hardness, durability, clarity and optical properties, and understanding these characteristics can help when choosing and caring for gemstone jewelry.
This guide introduces commonly used gemstones, explains how gemstones are evaluated, and explores topics including hardness, treatments, inclusions, gemstone cuts and care.
A gemstone is a natural material valued for characteristics such as beauty, rarity, color, transparency or durability and used for personal adornment and decorative objects.
Most gemstones are minerals, but not all are. Pearls, for example, are organic gems formed within mollusks rather than minerals formed through geological processes.
Gemstones can be transparent, translucent or opaque and occur in an extraordinary range of colors and crystal structures.
Gemstones may be natural, laboratory-grown or imitation, and these terms describe very different types of materials.
Natural gemstones form through geological or biological processes without human creation. They may still be cut, polished or treated after being recovered.
Laboratory-grown gemstones are created under controlled conditions and have essentially the same chemical composition and crystal structure as their natural counterparts.
An imitation or simulant resembles another gemstone in appearance but does not have the same chemical composition or crystal structure. Glass and other materials can be used to imitate natural gemstones.
Gemstones are evaluated using a combination of characteristics rather than a single universal standard. Important factors can include color, clarity, cut, carat weight, rarity, origin and whether the stone has been treated.
The relative importance of these characteristics varies between gemstone varieties. Color, for example, may be particularly important in many colored gemstones, while diamonds are commonly discussed using the standardized framework known as the Four Cs.
The Mohs scale measures a mineral's resistance to scratching. The scale ranges from 1 for very soft minerals to 10 for diamond, the hardest naturally occurring mineral on the scale.
Hardness is useful when considering how easily a gemstone's surface may become scratched, but hardness is not the same as overall durability.
A gemstone can be hard yet still vulnerable to chipping or breaking if it has cleavage, internal fractures or other structural characteristics. When choosing jewelry for frequent wear, both hardness and toughness should be considered.
Diamond is composed of carbon arranged in a crystal structure that gives it exceptional hardness. With a Mohs hardness of 10, diamond is highly resistant to scratching and is widely used in rings and other jewelry intended for frequent wear.
Diamonds occur naturally in a range of colors, although colorless and near-colorless diamonds are among the most familiar.
Diamonds are commonly evaluated using four characteristics known as the Four Cs:
These characteristics work together to influence the appearance and value of an individual diamond.
Sapphire is a variety of the mineral corundum. Blue is the color most commonly associated with sapphire, but sapphires naturally occur in many colors.
With a Mohs hardness of 9, sapphire is highly resistant to scratching and is suitable for many types of jewelry.
The color of sapphire is influenced by trace elements within the crystal structure, and variations in hue, tone and saturation contribute significantly to the appearance of an individual stone.
Ruby is the red variety of corundum, the same mineral family as sapphire. Its red color is primarily associated with chromium within the crystal structure.
Like sapphire, ruby has a Mohs hardness of 9 and is highly resistant to scratching.
Rubies can vary from lighter red to deeper, more saturated shades, and color is an important factor in their appearance.
Topaz is a transparent gemstone that occurs naturally in several colors. Blue topaz is especially familiar in contemporary jewelry and can range from pale sky blue to deeper blue tones.
Topaz has a Mohs hardness of 8, giving it good resistance to scratching. However, it has distinct cleavage and can be damaged by a sufficiently strong impact.
Blue topaz is among the gemstones used in Oliver Hampel's jewelry.
Tourmaline is a gemstone family known for an unusually broad range of colors. Individual stones can appear in shades of green, pink, red, blue and many other colors, and some crystals contain more than one color.
Tourmaline generally falls between 7 and 7.5 on the Mohs scale, making it suitable for many types of jewelry when worn with appropriate care.
The variety of colors available makes tourmaline particularly interesting for jewelry designs in which the gemstone becomes an important part of the composition.
Tourmaline is among the gemstones used in Oliver Hampel's work.
Quartz is one of the most abundant mineral families and occurs in many varieties. It has a Mohs hardness of 7 and is widely used in jewelry.
Amethyst is the purple variety of quartz. Its color can range from pale violet to deep purple.
Citrine is a yellow to orange variety of quartz. Natural citrine is relatively uncommon, and much of the citrine available commercially is produced by heat treating other varieties of quartz.
Aquamarine is a blue to blue-green variety of the mineral beryl. Its name refers to the color of seawater, and stones can range from very pale blue to more saturated blue-green tones.
Aquamarine has a Mohs hardness of approximately 7.5 to 8, providing good resistance to scratching for many jewelry applications.
Emerald is the green variety of beryl and belongs to the same mineral family as aquamarine. Its characteristic green color is associated primarily with trace amounts of chromium, vanadium or both.
Emerald has a Mohs hardness of approximately 7.5 to 8, but many emeralds contain inclusions and fractures that can make them more vulnerable to impact than their hardness alone might suggest.
For this reason, emerald jewelry should generally be handled and cleaned with care.
Pearls are organic gems formed within certain mollusks. Unlike mineral gemstones that are mined from the earth and then cut and polished, pearls develop their characteristic surface naturally as layers of nacre or other shell material form around an irritant or implanted nucleus.
Pearls are much softer than many mineral gemstones and require gentle handling. Cosmetics, perfume, chemicals and abrasive cleaning methods can damage their surfaces.
Pearls are used in selected Oliver Hampel jewelry designs, where their smooth, luminous surfaces provide a contrast to sculptural metal forms.
Gemstones may be treated to improve or alter characteristics such as color or clarity. Treatments are common within the jewelry industry and vary considerably depending on the gemstone.
Heat treatment, for example, is widely used with certain gemstones to modify color or clarity. Other treatments may involve irradiation, diffusion, filling, coating or the introduction of oils or resins.
Because some treatments can affect how a gemstone should be cleaned or repaired, knowing whether a stone has been treated can be important for long-term care.
Inclusions are internal features that formed within a gemstone or developed during its growth. They may include crystals, small fractures, growth patterns, fluids or other materials.
Inclusions are not automatically defects. They can provide information about how a gemstone formed and may help gemologists distinguish natural stones from laboratory-grown or imitation materials.
The visibility and location of inclusions can also influence a gemstone's appearance and, in some cases, its durability.
Cutting transforms gemstone material into a form designed to interact with light and work within a piece of jewelry.
Faceted gemstones use multiple polished surfaces to reflect and refract light. Common faceted shapes include round, oval, cushion, pear, emerald and marquise.
Cabochons have smooth, rounded surfaces rather than facets and are often used for opaque or translucent gemstones or stones whose optical effects are best displayed with a curved surface.
The choice of cut depends on the gemstone material, its natural shape and internal characteristics, and the visual effect the cutter or designer wants to achieve.
Choosing a gemstone is partly technical and partly personal. Color, shape, transparency, inclusions and the way a stone interacts with light can make one gemstone feel very different from another even when both belong to the same variety.
How the jewelry will be worn should also be considered. A gemstone intended for an everyday ring may need to withstand more impact and abrasion than a stone used in earrings or a pendant.
Rather than considering hardness alone, look at the overall durability of the gemstone, the jewelry design and the type of wear the piece is likely to experience.
In Oliver Hampel's contemporary jewelry, gemstones are integrated into the overall composition rather than treated simply as decoration. Color, light and the natural characteristics of the stone interact with sculptural metal forms and surfaces.
Gemstones and organic gems used in Oliver's work include diamonds, blue topaz, tourmaline, pearls and other gemstones selected for individual designs.
Learn more about Oliver's approach to contemporary jewelry on Meet Oliver Hampel.
The appropriate way to clean gemstone jewelry depends on the gemstone, any treatments it has received, the setting and the other materials used in the piece.
Many gemstones can be cleaned gently with a soft damp cloth or mild soapy water, but some stones should not be soaked or exposed to ultrasonic cleaners, steam, chemicals or sudden temperature changes.
Pearls and other delicate materials require particularly gentle care.
For detailed cleaning and storage recommendations, visit our Jewelry Care Guide.
