Garnet, gemstone of the month

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Garnet is a group of minerals and consists of more than 20 different species all having the same crystal structure but vary slightly in chemical composition. Only five of these species are economically available as gemstones. And come in a wide variety of colours.

Birthstone for the month of January: Garnet

Amazing find in a 5000-year-old Egyptian grave……….

 

Man have found red garnet bead necklaces in the graves of an Egyptian pharaohs, they were entombed with the mummified bodies to serve as valuable possessions for the afterlife.

In the ancient Rome carved garnets were set in signet rings, they were used to stamp the wax that secured important documents. In the Middle ages (475 to 1450 AD) red garnet was the favourite gem of nobility and clergy.

In central Europe the famous Bohemian garnets were discovered in 1500, in the Podsedice mine in the Bohemian Hills of the Czech Republic—formerly Czechoslovakia. This source remained the centre of the regional jewellery industry until the late 19th century. The stones were relatively small but of a fiery red colour.

 

Origin of the name

The name garnet comes from the pomegranate, as the red garnet resembles the colour of its seeds.

 

 

 

How are garnets formed?

Most garnets are formed in rocks that are altered by heat and pressure. Green garnets require more complex geological and chemical conditions.

 

What are garnets made of?

Garnet is a group of minerals and consists of more than 20 different species all having the same crystal structure but vary slightly in chemical composition.

Only five of these species are economically available as gemstones. And come in a wide variety of colours.

These are: pyrope, almandite, spessartite, grossularite and andradite.

 

Pyrope: a pure magnesium - aluminium garnet, medium to dark reddish orange red to slightly purplish red.

Pyrope garnets can be found in Myanmar, Thailand, Brazil, Tanzania, and Mozambique


Almandite: pure iron – aluminium garnet

Ranges in colour from reddish orange to red, slightly purplish red to reddish purple. The depth of colour depends on the iron content, the more iron, the deeper the red hue.

The major sources of almandine are: Sri lanka, India, Madagascar, Brazil, Greenland, Kenya, Tanzania, Pakistan and the US.

 

 

Spessartite can be found in a variety of orange and yellow.

It’s named after the Spessart district of Bavaria, Germany, where it was first discovered. were inconsistent. Today new deposits can be found in Madagascar, Namibia, Zambia, India, Pakistan, Sri Lanka, Brazil, and Nigeria.


In 1916, gem quality spessartite crystals were first discovered in an apartment building excavation in Manhattan at Haven Ave. & 179th. Street. A few years later gem spessartite crystals were discovered at construction sites at Riverdale Drive & 165th. street, and at a third locality at Washington Ave.

Grossularite consists of calcium and aluminium and there are two varieties: Hessonite and Tsavorite.

 

Hessonite is the warm yellow-orange to reddish orange variety of grossularite, it is often included and is also called cinnamon stone. Its colour is caused by a combination of iron and manganese.

Its localities are: India, Sri lanka, Brazil, Kenya, Tanzania and Mexico.

Tsavorite is the green to yellowish green variety and is coloured by vanadium.

It was named after the place of its discovery in the late 1970’s. The Scottish geologist and gemmologist Campbell Bridges (1937-2009) discovered this beautiful new garnet variety in the Tsavo national park in Kenya.

Although there are minor sources in Asia, the East African countries of Tanzania, Kenya, and Madagascar supply most of the world’s tsavorite.

Andradite is an iron and calcium garnet and demantoid is the highly prized variety. It owes its colour to a mixture of chromium and iron.

It was first discovered as greenish white pebbles by gold and platinum miners in Russia’s Ural Mountains in the mid-1800s. It immediately became popular with Russian nobility. Czar Nicholas II had jewellery made with demantoids for his wife.

Demantoid can be found in Russia and Africa (Namibia), Iran (Kerman), Italy, Greece, and Mexico. Demantoid is a rare and valuable gemstone sought by collectors.

Its colour is brilliant green and demantoid is one of the few gems that is prized for the presence of inclusions!

It may contain eye-visible fibre-like inclusions which gemmologist call horsetails.

 

 

Phenomenal garnets

Some garnets can show colour-change, from strong red under one light source and green, or even blue, under another. They are rare, and a real collector’s item. They can be found in Sri Lanka, Tanzania’s Umba Valley and Madagascar.

Star garnets also occur but they are not as rare as colour-change stones, they contain rutile silk needles that cause asterism.

Four-rayed stars are common, but some stones show six rays, or even a combination of four and six rays in the same stone. Star garnets are found in India, Sri Lanka, and the US state of Idaho.

Cat’s eye garnets are rare, an eye effect is caused the reflection of light on parallel mineral fibres.

Care and cleaning of your garnet.

Hardness and toughness

The hardness of garnet varies with type and ranges from 6.5 to 7 on the hardness on the Mohs scale. Demantoid is the softest and pyrope, almandite, spessartite and tsavorite are the hardest varieties.

Garnets are durable enough for jewellery if they are not subjected to hard blows or rough wear.

Stability

Garnet are stable to light and chemicals but can be attacked by hydrofluoric acid.

Cleaning

The best way to clean your garnet jewellery is warm soapy water, this is always safe.

Ultrasonic cleaning is safe except for fractured stones.

Steam cleaning is not recommended.

 

BIRTHSTONES & ANNIVERSARIES

Garnet is the birthstone for January and symbolizes the 2nd anniversary

 

 

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