Pearls
Pearls are formed in clams, oysters and mussels by the secretion of a substance known as nacre around an irritant in the outer tissue of the organism, or between the outer tissue and the shell. Only a few species are capable of producing pearls and can secrete the nacreous coating that has the attractive pearly luster of gem pearl. Nacre is also the substance that coats the inner surface of their shells (called mother-of-pearl). In most species, nacre forms at a slow 0.6mm of a mm a year.
Natural pearls: Forming by the chance entering of an irritant into the oyster, a natural pearl only forms in about 1 of 40 pearl producing oysters. Due to the slow rate of growth and the relatively short lifespan of the oyster, large sized natural pearls are rare and usually not round. Found in the Persian Gulf (considered the finest natural pearls in the world), the Gulf of Manaar, the Red Sea, the north and northwest coast of Australia, Burma, Tahiti, New Guinea, Borneo, and Venezuela.
Cultured pearls: These pearls grow around a nucleus that has been manually placed within an oyster. This practice dates back to the 13th century Chinese, but was only perfected in the early part of the 20th century by the Japanese.
Before the modern culturing techniques, a round nucleus, usually composed of clam or oyster shell, was placed between the the mantle and shell of the oyster and allowed to grow for 2 or 3 years. In modern cultured pearls the nucleus (a bead composed of freshwater clam shell wrapped with a strip of the mollusc's mantle) is placed within the mantle or gonad of the oyster, away from the shell, allowing it to grow freely.
The size of resulting pearls depend on the size of the nucleus, the mollusc species, the temperature and chemistry of the water, and the time allowed for growth. Several pearls may be grown in a single oyster, but these will be smaller than if a single nucleus is inserted. Growth periods are from 2 to 7 years and figures suggest only 25% produce a cultured pearl. Japan and Australia are significant producers of cultured pearls. Australia uses an indigineous oyster that produces typically large sized white or silvery pearls.
Cultured black pearls are found in oysters off Peru, Baja California, Panama, certain islands of Indonesia, Micronesia, the Philippines, Okinawa, and French Polynesia (Tahiti and adjacent islands). Only from the latter have cultured black pearls been produced in large numbers. These pearls are large and have a high growth rate as well as superior lustre.
Freshwater Pearls / Freshwater Cultured Pearls: The process of natural freshwater pearls occurring is pretty much the same as other pearls, except one occurs in mussels (freshwater) and the other in oysters (saltwater) respectively. Cultured freshwater pearls are created by either 1) inserting a small piece of live mantle tissue (from another mussel) directly into the pearl producing mussel. These are composed entirely of nacre, just like their natural counterparts. 2) inserting a shape into the mussel in a like manner to the creation of cultured pearls to create "coin" and other shaped pearls. A mussel can grow up to 60 pearls at a time!
Blister pearls: When the oyster or mussel was coating the pearl it also coated the shell lining, resulting in a pearl that was attached to the shell.
Keshi pearls: These are formed when an oyster or mussel rejects and spits out the nucleus implanted during the process of producing cultured pearls. Because the nucleus has been expelled by the oyster, the resulting pearl is all nacre and they often have a wonderful lustre. Also known as Petal Pearls.
Colour of pearls: Natural colours vary from creamy white to yellow, pink, green, lavender, and grey to black. Colours are caused by the amount of conchiolin and aragonite present in the nacre and by the quality of the water in which the oyster or mussel lives. The freshwater pearls' natural colors include white, cream, lavender, pink, orange, gold and gray. White pearls are often bleached to remove any undesirable faint colour. Freshwater pearls are frequently treated (either by irradiation or dyeing) to create a veritable rainbow of colours.
Other terms used to describe pearls:
Lustre - the shiny exterior of the pearl. The way pearls seem to glow from within and is based on the depth of reflection.
Bodycolor - the underlying color of the pearl.
Overtone - a translucent layer of color. Not all pearls have an overtone.
Irridescent orient - the variable play of colors across the surface of the pearl like a rainbow. Not all pearls have iridescent orient.
There are many imitation pearls - eg. glass, acrylic, on the market and some look and feel very realistic. Please check the description thoroughly when purchasing 'pearls' and if in doubt, don't be afraid to ask the vendor. If they can't sufficiently answer your question, look elsewhere.
Considered magic charms, symbols of purity and love, or sources of wisdom and power, pearls are one of the oldest known gems in the world having been worn in civilized Middle East and Asian societies as early as 3500 BC. India`s Hindu god Krishna was credited with discovering pearls when he took one from the sea and presents it to his daughter Pandaïa on her wedding day. Medieval knights wore them for protection in battle. The Greeks associated the pearl with love and marriage. Ancient Romans saw pearls as the ultimate symbol of power and wealth - a pearl earring reportedly paid for one Roman general`s political campaign!
Peridot
Colour: green, yellow-green
Hardness: 6.5-7
Cleavage: indistinct
Fracture: brittle, small conchoidal
Crystal system: orthorhombic
Chemical composition: magnesium iron silicate
Transparency: transparent
Strong double refraction
Colouring agent: Iron
From the Olivine branch of minerals, the name peridot may come from the Arabic word for gem faridat. In early times peridot was often referred to, along with other similarly coloured stones, as chrysolite. Peridot is mentioned in the Bible under the Hebrew name of pitdah and was probably used in the fabled Breastplate of the Jewish High Priest.
An ancient mine of peridot is on the island of Zabargad in the Red Sea – it was mined for over 3500 years and then lay undisturbed for centuries before being rediscovered at the turn of the 20th century. The lasrgest cut stone known is from this mine and weighs 319ct. Peridot was brought to central Europe by the crusaders and many were presented to churches as ‘emeralds’. In Russia, there are some peridots which came out a meteorite that fell in Siberia in the 18th century!
Usually found in only smaller sizes, peridot is also found in Australia, Brazil, China, Kenya, Mexico, Pakistan, Sri Lanka, South Africa,, Tanzania, Norway and the USA.
Peridot may be confused with chrysoberyl, garnet, emerald, prasiolite, beryl, prehnite and tourmaline.
Peridot is believed to cleanse and to understand your destiny. It is also believed to alleviate jealousy, resentment and anger and to reduce stress. Banishing lethargy it has a tonic effect, strengthening the metabolism and benefiting the skin. In ancient times it was believed to keep away evil spirits.
Prasiolite
Colour: leek-green.
Hardness: 7
Cleavage: none
Fracture: brittle, conchoidal
Crystal system: trigonal
Chemical composition: silicon dioxide
Transparency: transparent
Prasiolite – the greek word for ‘leek green stone’ is not found in nature, but is produced by heating amethyst or citrine. Sometimes referred to as ‘green amethyst’.
Prehnite
Colour: yellow-green, brown-yellow
Hardness: 6-6.5
Cleavage: good
Fracture: uneven
Crystal system: orthorhombic and massive.
Chemical composition: calcium aluminium silicate
Transparency: transparent to translucent
Named after the Dutch Colonel Hendrick von Prehn who first introduced prehnite into Europe, it is found in Australia, China, Sctoland, South Africa and the USA. Can be confused with apatite, chryoprase, jade, peridot, and serpentine.
Metaphysically, prenite is considered to be the crystal that heals the healer. It is believed to enhance inner knowing and to always be prepared. It can calm the environment and bring peace and protection, bringing harmony with nature. Good for Feng Shui, it can assist you to declutter and organize effectively. In healing it is particularly good for diagnosis.
Pyrite
Colour: brass yellow, gray-yellow
Hardness: 6-6.5
Cleavage: indistinct
Fracture: uneven, brittle, conchoidal
Crystal system: cubic
Chemical composition: iron sulphide
Transparency: opaque
Pyrite can cause sparks when knocked against iron, and its name indeed is from the Greek word for fire. Due to its gold colour it is often referred to as ‘fools gold’. Long used for adornment, pyrite jewellery has been found in ancient Greek, Roman and Inca civilizations. Native Americans believed that pyrite ‘mirrors’ allowed you to see inside the soul.
Pyrite deposits are in Peru, Bolivia, Mexico, Romania, Sweden, Spain, Italy, France and the USA.
Metaphysically, pyrite is considered to be an excellent energy shield, deflecting harm and danger and assisting one to see truth behind the façade. It is also believed to relieve anxiety and frustration while increasing confidence. In healing it is believed to help the lungs, digestive and circulatory systems.
Quartz - Rose
Colour: pale to strong pink
Hardness: 7
Cleavage: none
Fracture: brittle, conchoidal
Crystal system: trigonal but mostly found in a massive form
Chemical composition: silicon dioxide. Colouring agent – titanium.
Transparency: semi transparent to translucent
Rose quartz, named after its pink colour, is often crackled and usually turbid. Found in Brazil, Madagascar, India, Mozambique, Namibia, Sri Lanka and the USA. Can be confused with kunzite, morganite and topaz.
Metaphysical – a stone of unconditional love and infinite peace. In healing it is believed to strengthen the physical heart and circulatory system, alleviates vertigo and is helpful in Alzheimers, Parkinsons and senile dementia.
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Quartz - Rock Crystal
Colour: colourless
Hardness: 7
Cleavage: none
Fracture: brittle, conchoidal
Crystal system: trigonal
Chemical composition: silicon dioxide
Transparency: transparent
Rock Crystal – the name crystal comes from the Greek word for ‘ice’ as it was believed that rock crystal was eternally frozen. There are many myths regarding rock crystal – in Japanese myth quartz formed from the breath of a white dragon and in the first century, a mystic named Apollinus of Tyana used quartz to "transport" himself. Apparently he dematerialized and materialized in the presence of Caesar Domitian and used the gem to disappear and reappear at the foot of Mt. Vesuvius.
Found worldwide, huge crystals weighing tons have been found although rarely of cuttable material. Rock crystal can have inclusions of goethite, gold, pyrite, rutile and tourmaline. It can be confused with other colourless gems as well as glass imitations.
Metaphysical – quartz is a powerful healing and energy amplifier. For healing it is considered a master healer, stimulating the immune system and bringing the body into balance. Natural rainbows are found within many quartz crystals and this stone draws off negativity and disperses healing energy to the body and environment.
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Quartz - Smoky
Colour: brown to black, smoky grey
Hardness: 7
Cleavage: none
Fracture: brittle, conchoidal
Crystal system: trigonal
Chemical composition: silicon dioxide
Transparency: transparent
Smoky Quartz - Named after its smoky colour it can sometimes be known as ‘morion’ and ‘cairngorm’. The colour is caused by natural gamma rays although clear (rock crystal) quartz can also be irradiated to smoky quartz.
Found in worldwide although larger producers are Brazil, Madagascar, Russia, Scotland, Switzerland and Ukraine. Can be confused with andaulsite, idocrase and tourmaline.
Metaphysical – a grounding stone that helps with stress, dealing with difficult times and depression. In healing it is believed to be effective for ailments of the abdomen, hips and legs.
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Rhodochrosite
Colour: rose-red to yellowish, striped
Hardness: 4
Cleavage: perfect
Fracture: uneven, conchoidal
Crystal system: trigonal
Chemical composition: manganese carbonate
Transparency: transparent to opaque
Rhodochrosite’s name is derived from the Greek word for ‘rose coloured’. Usually found in a massive, opaque form, it is occasionally found as a transparent crystal which is highly prized. The massive form has stripes and zigzag bands in a mixture of pinks and raspberry red.
An important source of rhodochrosite is in Argentina, where in an abandoned Inca silver mine, the rhodochrosite has formed as stalagmites. Indeed it is sometimes called ‘Inca Rose’. Apparently Incan belief was that rhodochrosite was the blood of their former kings and queens, solidified into stone. It is also found in Chile, Mexico, Peru, South Africa and the USA.
Often confused with rhodonite.
Metaphysically, rhodochrosite enhances compassion, attracts soulmates and encourages spontaneous expression of feelings.
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Rhodonite
Colour: dark red, flesh red with black, sometimes with yellow tint.
Hardness: 6.5-6.5
Cleavage: perfect
Fracture: uneven, conchoidal, tough
Crystal system: triclinic but usually found in a massive form
Chemical composition: manganese silicate
Transparency: transparent to opaque
As with rhodochrosite, rhodonite, is derived from the Greek word rhodos for ‘rose’. Its pink-red colour usually has black dendritic inclusions of manganese oxide and it is only rarely found in a transparent form. Amazingly it has been used for wall tiles in a subway in Moscow!
Found in Australia, Finland, New Zealand, Japan, England, Canada, Madagascar, Mexico, Russia, Sweden, South Africa, Tanzania and the USA.
Most often confused with rhodochrosite.
It is believed that rhodonite can be used as an emotional balancer – useful to heal emotional shock and panic and to reduce emotional wounds. It has also been used to turn back insults and to prevent retaliation. In healing it is believed to assist healing of wounds and insect bites.
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Rhyolite
Colours: light gray, pink, yellowish, cream, mauve, tan to medium brown, light to brick-red; mottled or banded patterns are relatively common.
Hardness 6-7
Crystal system: amorphous
Chemical composition: a mixture of quartz and orthoclase feldspar with small amounts of plagioclase feldspar, biotite mica, amphiboles, and pyroxenes
The name rhyolite is derived from the Greek word for stream - apparently given in allusion to the flow banding that can be characteristic. This name was first applied in literature in 1860 by Baron Ferdinand von Richthofen (grandfather to the infamous ‘red baron’ of WWI).
Chemically similar to granite, rhyloite is a fine grained volcanic rock that cooled too quickly to form into crystals. It is sometimes called ‘rainforest jasper’ and ‘wonderstone’. Many rhyolites intergrow with quartz,feldspar plus and plagioclase. Notable deposits are in Australia and the USA although it is found on all continents.
Metaphysically, rhyolite represents change, variety and progress. It is said to enhance creativity and help with self-realization, to balance the emotions and increase self-respect, self-worth and the capacity to love.
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Ruby
Colour: red
Hardness: 9
Cleavage: none
Fracture: conchoidal, splintery, brittle
Crystal system: trigonal
Chemical composition: aluminium oxide – colouring agents chromium and sometimes iron.
Transparency: transparent to opaque
Ruby – from the Latin ruber meaning red. A number of red stones such as spinel and garnet were also called ruby till the 19th century.
The most desirable colour for ruby is referred to as ‘pigeons blood’ – a pure red with a hint of blue. As colour is the determinant, paler stones may be classified as pink sapphire rather than ruby. Inclusions are common and the colour is often uneven. Heat treatment is common to enhance the colour.
Although it can be found in its host rock, most ruby is from alluvial deposits. Found in Burma, Thailand, Sri Lanka, Tanzania, Afghanistan, Cambonia, Kenya, Madagazcar, Vietnam, Australia, Brazil, India, Malawi, Nepal, Pakistan, USA and Zimbabwe.
The largest known gem rough was found in Burma, weighed 400 carats and was cut into three stones. Large, famous stones (sich as the Black Prince’s Ruby in the English state crown) that were previously thought to ruby have been proven to be red spinel. Ruby can also be confused with garnet, topaz, tourmaline and zircon. Synthetic rubies and imitations abound.
Metaphysical – an energetic stone, it encourages a passion for life and motivates but can also over stimulate. A stone of abundance it helps retain wealth and passion. For healing purposes it is believed to detoxify the body, blood and lymph and treats fevers and infectious diseases.
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