Gemstone jewellery (guide)

The value of a precious or semi-precious stone is mainly determined by its rarity, hardness, colour intensity, and transparency. Gradations in colour richness or reduced transparency, resulting from inclusions or impurities in the stones, also impact their quality. Depending on the type of stone, these quality features have a significant or minor effect on the overall value of the stone. For diamonds, the 4 C's are used as criteria for value and quality. The 4 C's stand for Cut, Colour, Clarity, and Carat. For more detailed information on these criteria, you can refer to our Diamond Guide.

Gemstones and semi-precious stones form deep within the Earth. The formation process takes three to ten million years and requires immense pressure and high temperatures. There are three different types of rocks in which gemstones and semi-precious stones have formed: Igneous rock, metamorphic rock, and sedimentary rock. Some gemstones and semi-precious stones form during the cooling of liquid magma in igneous rock, where the minerals contained crystallize under the pressure inside the Earth (e.g., granite, obsidian, and peridotite). They can also form through a metamorphic process when liquid magma penetrates existing rock formations (e.g., jade, emerald, garnet, and lapis lazuli). The secondary mineral formation in sedimentary rock also produces gemstones and semi-precious stones. This happens through the deposition of sediments or the weathering process (e.g., jasper, onyx, marble, azurite, malachite, various opals, and turquoise). Through volcanic activity, the valuable stones are brought to the Earth's surface. Therefore, gemstones and semi-precious stones are mostly found in mountain ranges but also in riverbeds, on the seafloor, or in dried-up bodies of water.

Moissanite

• Mineral Type: Silicon Carbide
• Hardness: 9.5
• Colour: Transparent with a rainbow-coloured luster
• Occurrence: Extremely rare
• Locations: In small quantities in the upper layers of the Earth and in meteorites; mostly produced in laboratories nowadays

For more information, you can refer to our encyclopedia entry on Moissanite.

Ruby

• Mineral Type: Variety of Corundum (Aluminum Oxide)
• Hardness: 9
• Colour: Red (with varying shades of pink and purple)
• Occurrence: Very rare
• Locations: Myanmar, Madagascar, Mozambique, Kashmir, Afghanistan, among others

For more information, you can refer to our encyclopedia entry on Ruby.

Sapphire

• Mineral Type: Variety of Corundum (Aluminum Oxide)
• Hardness: 9
• Colour: Dark blue, navy blue, and cornflower blue; but also yellow, pink, salmon-coloured (Padparadscha Sapphire), and white (Leuco Sapphire)
• Occurrence: Very rare
• Locations: Sri Lanka, Myanmar, Madagascar, Kashmir, Australia, Cambodia, among others

For more information, you can refer to our encyclopedia entry on Sapphire.

Emerald

• Mineral Type: Variety of Beryl
• Hardness: 7.5 - 8
• Colour: Green
• Occurrence: Rare
• Locations: Colombia, Brazil, Zambia, Afghanistan, Russia, Madagascar

For more information, you can refer to our encyclopedia entry on Emerald.

Blue Topaz

• Mineral Type: Variety of Topaz (Silicate)
• Hardness: 8
• Colour: Light blue; Sky Blue Topaz, Swiss Blue Topaz, and London Blue Topaz
• Occurrence: Very rare
• Locations: Zimbabwe, Namibia, Norway, Madagascar, USA

For more information, you can refer to our encyclopedia entry on Blue Topaz.

White Topaz

• Mineral Type: Variety of Topaz (Silicate)
• Hardness: 8
• Colour: Purest form of Topaz, contains no colour-inducing elements
• Occurrence: Common
• Locations: Northern Ireland, Australia, Germany

For more information, you can refer to our encyclopedia entry on White Topaz.

Amethyst

• Mineral Type: Variety of Quartz (Silicon Dioxide)
• Hardness: 7
• Colour: Purple
• Occurrence: Relatively rare
• Locations: Brazil, Uruguay, Madagascar, Zambia, Morocco, India, USA, Russia

For more information, you can refer to our encyclopedia entry on Amethyst.

Citrine

• Mineral Type: Variety of Quartz (Silicon Dioxide)
• Hardness: 7
• Colour: Pale yellow to orange-brown
• Occurrence: Very rare
• Locations: Russia (Ural), Argentina, Burma, Brazil, Spain, France, India, Bolivia, USA

For more information, you can refer to our encyclopedia entry on Citrine.

Garnet

• Mineral Type: Silicates and Germanates
• Hardness: 7
• Colour: Dark red; can also be yellow, green, or black
• Occurrence: Common
• Locations: USA, Brazil, Sri Lanka, South Africa

For more information, you can refer to our encyclopedia entry on Garnet.

Peridot

• Mineral Type: Particularly pure variety of the mineral olivine
• Hardness: 6.5 - 7
• Colour: Light green
• Occurrence: Common
• Locations: Pakistan, China, USA, Myanmar, Egypt, Tanzania

For more information, you can refer to our encyclopedia entry on Peridot.

Smoky Quartz

• Mineral Type: Variety of Quartz (Silicon Dioxide)
• Hardness: 7
• Colour: Grayish-brown to black
• Occurrence: Common
• Locations: Australia, Brazil, Madagascar, Russia, Switzerland, Scotland, Ukraine, USA

For more information, you can refer to our encyclopedia entry on Smoky Quartz.

Agate

• Mineral Type: Variety of Quartz (Silicon Dioxide)
• Colour: Colourful (striped pattern in various Colour variations)

For more information, you can refer to our encyclopedia entry on Agate.

Alexandrite

• Mineral Type: Variety of Chrysoberyl (Silicate)
• Colour: Green to red

For more information, you can refer to our encyclopedia entry on Alexandrite.

Ametrine

• Mineral Type: Variety of Quartz (Combination of Amethyst and Citrine)
• Colour: Violet to yellow

For more information, you can refer to our encyclopedia entry on Ametrine.

Apatite

• Mineral Type: Phosphates, Arsenates, Vanadates
• Colour: Red, green, yellow, blue, or yellow-green

For more information, you can refer to our encyclopedia entry on Apatite.

Aquamarine

• Mineral Type: Variety of Beryl (Silicate)
• Colour: Light blue

For more information, you can refer to our encyclopedia entry on Aquamarine.

Aventurine

• Mineral Type: Variety of Quartz (Silicon Dioxide)
• Colour: Green

For more information, you can refer to our encyclopedia entry on Aventurine.

Rock Crystal

• Mineral Type: Variety of Quartz (Silicon Dioxide)
• Colour: Transparent with a glassy sheen

For more information, you can refer to our encyclopedia entry on Rock Crystal.

Beryl

• Mineral Type: Silicates and Germanates
• Colour: Clear and colourless; occurs in various colour varieties due to trace elements (Green, Blue, Pink)

For more information, you can refer to our encyclopedia entry on Beryl.

Hematite

• Mineral Type: Metal Oxide
• Colour: Black

For more information, you can refer to our encyclopedia entry on Hematite.

Jade

• Mineral Type: Jadeite (Augite Group)
• Colour: Green

For more information, you can refer to our encyclopedia entry on Jade.

Carnelian

• Mineral Type: Variety of Chalcedony (Silicon Dioxide)
• Colour: Brown

For more information, you can refer to our encyclopedia entry on Carnelian.

Cat's Eye

• Mineral Type: Variety of Quartz (Silicon Dioxide)
• Colour: Yellow-green

For more information, you can refer to our encyclopedia entry on Cat's Eye.

Kunzite

• Mineral Type: Variety of Spodumene (Lithium-Aluminum-Silicate)
• Colour: Pink to violet

For more information, you can refer to our encyclopedia entry on Kunzite.

Kyanite

• Mineral Type: Silicates and Germanates
• Colour: Blue

For more information, you can refer to our encyclopedia entry on Kyanite.

Lapis Lazuli

• Mineral Type: Composed of varying proportions of the minerals Lazurite, Pyrite, Calcite, and traces of Sodalite and Diopside
• Colour: Deep blue and glossy

For more information, you can refer to our encyclopedia entry on Lapis Lazuli.

Malachite

• Mineral Type: Copper Carbonate
• Colour: Green

For more information, you can refer to our encyclopedia entry on Malachite.

Marcasite

• Mineral Type: Iron Disulfide
• Colour: Dark bronze tone

For more information, you can refer to our encyclopedia entry on Marcasite.

Morganite

• Mineral Type: Variety of Beryl (Silicate)
• Colour: Pink to violet

For more information, you can refer to our encyclopedia entry on Morganite.

Onyx

• Mineral Type: Variety of Chalcedony (Silicon Dioxide)
• Colour: Black and white

For more information, you can refer to our encyclopedia entry on Onyx.

Opal

• Mineral Type: Oxides and Hydroxides
• Colour: Colourless or with milky, gray, red, yellow, or brown hues in various intensities

For more information, you can refer to our encyclopedia entry on Opal.

Quartz

• Mineral Type: Silicon Dioxide
• Colour: Transparent and colourless; can also occur in various colour varieties

For more information, you can refer to our encyclopedia entry on Quartz.

Rose Quartz

• Mineral Type: Variety of Quartz (Silicon Dioxide)
• Colour: Pink

For more information, you can refer to our encyclopedia entry on Rose Quartz.

Tanzanite

• Mineral Type: Zoisite
• Colour: Blue

For more information, you can refer to our encyclopedia entry on Tanzanite.

Titanite (Sphen)

• Mineral Type: Calcium Titanium Silicate
• Colour: Colourless; can also be brown, yellow, green, gray, or black

For more information, you can refer to our encyclopedia entry on Titanite.

Turquoise

• Mineral Type: Copper Aluminum Phosphate
• Colour: Turquoise

For more information, you can refer to our encyclopedia entry on Turquoise.

Tourmaline

• Mineral Type: Silicate
• Colour: Blue, green, red, pink, brown, and black (sometimes in a single crystal)

For more information, you can refer to our encyclopedia entry on Tourmaline.

Jewellery with gemstones requires special care, as the stones vary depending on their type. Below, we have compiled some useful tips for handling gemstone jewellery:

• Store your jewellery pieces in separate compartments of a jewellery box to avoid scratches
• Put on your gemstone jewellery after using cosmetics, hairspray, or perfume to prevent discolouration of the stones
• Remove your gemstone jewellery before sports or other activities that could damage the jewellery
• Learn in advance about the specific care suitable for your particular stone
• Do not use common cleaning agents for cleaning unless you are sure they are suitable
• Clean your jewellery regularly with a damp, lint-free cloth to quickly eliminate possible impurities

In general, most gemstones can be cleaned with a lint-free cloth. For some gemstones, cleaning in a warm water bath with a little soap is possible. This cleaning method can be safely used, especially for rubies and sapphires. Cleaning methods such as steam or ultrasonic cleaning offer particularly thorough cleaning of gemstone jewellery. However, they are not suitable for every precious and semi-precious stone and should only be used if you are certain they will not damage the respective stone.

Gemstone jewellery, with its beautiful array of colours, possesses a special allure. Serving as a symbol of immortality, wealth, and power, precious and semi-precious stones have been coveted for millennia. Since ancient times, gemstones have been crafted into jewellery alongside gold, silver, and other materials, with mystical or healing powers attributed to them. Hence, gemstones are often worn as amulets and talismans.

From this tradition emerged the practice of birthstones. With the introduction of the Gregorian calendar, a specific gemstone was assigned to each month. Wearing the gemstone of one's respective birth month was believed to enhance its healing effects. Thus, individuals could carry the gemstone of their birth month as a piece of jewellery. Birthstones are said to amplify the positive character traits associated with a particular zodiac sign. Moreover, as everyday companions, they are believed to protect and bring luck to their wearers.