What are gemstones?

Gemstones include minerals, but also rocks or natural glasses. Gemstones have a hardness level of less than 8 on the Mohs scale, have low light refraction, are colder in color and are more common than precious stones, and are therefore much cheaper. Characteristic inclusions can also occur in gemstones and are important features for distinguishing them.

Mineral class : The violet to red-violet amethyst belongs to the group of oxides. Its Mohs hardness is 7 and is therefore one of the hard minerals. The amethyst is a variety of quartz.

Color : The color scale ranges from pink to a very light to a very dark violet. The distribution of the color in the crystal is usually irregular. If the amethyst is heated, it changes its color to yellow or brown, and thus becomes citrine.

Occurrence : Amethyst is relatively widespread, but there are relatively few clear and large specimens suitable for making gemstones. It is found in India, Madagascar, Australia and Canada. One of the largest amethyst deposits is in Lower Austria.

Mineral class : This gemstone consists of a rare variety of quartz, namely the violet amethyst and the golden yellow citrine.

Color : Ametrine has a color scale from violet to golden yellow, with lighter and darker gradients. If the gemstone is viewed in sunlight, its natural color can be seen.

Occurrence : The most beautiful ametrines come from the eastern Andean region of Bolivia.

Aquamarin

Mineral class : Aquamarine is a variety of the beryl group and has a Mohs hardness between 7.5 and 8.

Color : The color of aquamarine ranges from light to deep blue to blue-green. The stone gets its blue color from the iron it contains. Aquamarine is dichroic, which means that the stone changes color from almost colorless to deep blue when the angle of view or the lighting changes.

Occurrence : Aquamarine deposits are found all over the world, the most important are in Brazil. Other important locations are in Mozambique, Madagascar, Pakistan and Nigeria.

Mineral class : This gemstone is classified in the mineral class of silicates and is very common. The beryl group mainly includes aquamarine, bixbite, goshenite, emerald, morganite, heliodor and yellow beryl. Beryls have a Mohs hardness of 8.

Colour : The beryl group includes six colour varieties.

• Aquamarine: various shades of blue up to blue-green
• Bixbit: intense red
• Goshenite: colorless
• Emerald: Green
• Morganite: light pink to salmon
• Heliodor: light yellow to yellow-orange

Distribution : The most important locations are in Pakistan, Africa and South America.

Mineral class : Chalcedony is a variety of quartz. One of the most famous representatives of the chalcedony group is agate, whose characteristic feature is its multi-colored banding. Onyx is the name for agate in the colors black and white.

Another member of the group is the green to blue-green aventurine, which has an impressively shimmering surface due to plate-shaped inclusions of foreign minerals. Carnelian is an orange-red to brown-red variety of chalcedony. The green heliotrope owes its nicknames blood jasper and bloodstone to its striking red speckles.

Color : Chalcedony is characterized by its blue-white to grayish shimmer. However, the chalcedony group comes in numerous colors - such as black in onyx or "banded," i.e. multicolored, like agate.

Distribution : Namibia, Turkey, India, Russia, Brazil and Germany.

Mineral class : Citrine is a variety of quartz, has a Mohs hardness of 7 and is therefore one of the hard minerals.

Color : The inclusions of iron oxide give the gemstone its pale yellow to brown-orange color. If an amethyst is heated, it changes color to yellow or brown, and becomes citrine.

Occurrence : Citrine is found in parts of Russia, Argentina, Brazil, India, Spain, and France. Natural citrines are rare.

Mineral class : the varieties of the garnet group are impressive due to their variety of colors, clarity, hardness and rarity. The gemstone has a hardness of 7.5 on the Mohs scale. Many gemstones, such as melanite, pyrope, almadine or rhodolite: its special color range extends from pink to dark red and can have tendencies towards violet or raspberry red.

Color : This gemstone has all color variations – from colorless, to red, orange, green, to black in all shades.

Occurrence : Africa, India, Sri Lanka, Austria, Czech Republic, Slovakia, Russia, North Carolina, USA (Rhodolite), etc.

Mineral class : Jadeite is the mineralogical name; in trade, it is usually referred to as jade. Jadeite is a transparent, translucent or opaque gemstone. The most sought-after is the transparent, emerald green gemstone, which is also called "Imperial Jade" or "King's Jade" or "Yan Jade". Its Mohs hardness is 6.5 to 7. Warning: no other stone is counterfeited as often as jade!

Color : colorless to black.

Distribution : mainly Myanmar and China.

Mineral class : Kunzite belongs to the mineral family of the spodumene gemstone group and has a Mohs hardness of 6.5 to 7.

Color : The color variations of kunzite are due to inclusions of iron (yellow and green shades), chromium (green shades) and manganese (pink to red-violet shades).

Occurrence : Kunzite deposits are found in Afghanistan, Madagascar, Pakistan and California. The gemstone was only discovered at the beginning of the 20th century.

Mineral class : Malachite is a green, transparent copper mineral with dark green bands. The gemstone has a Mohs hardness of only 4 and is therefore relatively unsuitable as a ring stone. It is also sensitive to heat, acids and alkalis, soaps and cosmetics and must therefore be handled with a certain degree of caution.

Color green

Occurrence : Russia, Congo

Mineral class : Moonstone is a gemstone from the feldspar group, which has the characteristic feature of a silver to blue-gray shimmer - the so-called "adulasing". Its hardness according to Mohs is 6. They are sensitive to heat, acids and alkalis, soaps and cosmetics and must therefore be handled with a certain degree of care.

Color : from colorless to black.

Occurrence : widespread, also in Austria (Zillertal)

Mineral class : Opal is a common gemstone from the group of oxides and hydroxides. Its hardness according to Mohs is about 5.5 to 6.

Color : When it comes to opals, a distinction is made between the ordinary opal and the precious opal. The precious opal catches the eye with its colorful play of colors. The stone changes its color when the angle is changed.

Occurrence : The best known location for precious opals is Australia.

Mineral class : Peridot is a transparent, very brittle variant of the mineral olivine. Its hardness on the Mohs scale is approximately 6.5 to 7. In the past, it was also called "chrysiolite", but according to CIBJO, this is no longer a commercial name.

Color of the gemstone : olive green, yellow green, brown green.

Distribution : Zeberged Island in the Red Sea, Myanmar, China, South Africa, Arizona (USA), Brazil, Australia, etc.

Mineral class : The gemstone prasiolite, also known as green amethyst or vermarine, is a variety of quartz. The Mohs hardness of the gemstone is 7.

Colour : The typical colour of prasiolite is leek green with white streaks.

Occurrence : Parasiolite is very rare and is found mainly in Brazil. Other deposits are found in England and Poland.

Mineral class : The gemstone quartz belongs to the mineral class of oxides. The mineral has a Mohs hardness of 7, which means it is one of the hard minerals and serves as a reference value on the Friedrich Mohs scale.

Color : The quartz group includes a variety of varieties. Here are some examples:

• Amethyst: pink through a very light to a very dark violet
• Ametrine: violet to golden yellow
• Citrine: yellow to orange-brown in color
• Prasiolite: leek green and transparent
• Smoky quartz: smoky to black colored

Occurrence : Quartz is formed mainly in cracks and veins in natural cavities and can therefore be found all over the world.

Mineral class : Tanzanite is a variety of the zoisite group. The Mohs hardness of a tanzanite is between 6.5 and 7.

Color : Tanzanite is available in a bright blue to a strong violet. By changing the viewing angle, the stone appears in purple red, bronze or even blue.

Occurrence : The gemstone tanzanite is very rare. There is only one place in the world where the stone is mined, namely in East Africa.

Mineral class : The gemstone tourmaline forms a group of its own, which is one of the most beautiful and colorful of all. The hardness is approximately 7 to 7.5 on the Mohs scale. Tourmalines are not yet produced synthetically.

Colour : Tourmalines come in all colours, from colourless to black. One species of colour is the occurrence of tourmalines from deposits in Brazil, with sensational colours – these are known as Paraiba colours.

Distribution : Brazil, Sri Lanka, Myanmar, Africa, USA, Urals, Afghanistan.

Mineral class : The gemstone turquoise forms its own mineral class.

Color : Turquoise is available in the sea colors sky blue, blue green and apple green. The most popular turquoise is sky blue.

Occurrence : The largest mining area for turquoise is in Iran. Other deposits are located in Australia, Brazil, China, Mexico and the USA.