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Coloured gemstones

Every gemstone is unique and Gowan Jewellers is happy to provide a selection of stones
on approval for you to view at the shop.  You can then see the differences in colour, clarity, size and shape for yourself,  according to your requirements and budget. I am very happy to give advice
with regard to the suitability of different stones for certain designs. This page is a guide to
the most popular gemstones with a few examples shown and their general properties explained
but if you have any questions please contact me by telephone or email for free, professional advice.

You will be under no obligation to buy.

Sapphire belongs to the corundum group,  which has  excellent hardness with 9 on the Mohs scale (exceeded only by that of the diamond) so that sapphires are easy to look after and suitable for everyday wear. Corundum is a pure aluminium oxide which crystallised into wonderful gemstones a long time ago as a result of pressure and heat at a great depth. The presence of small amounts of other elements, especially iron and chrome, are responsible for the colouring, turning a crystal that was basically white into a blue, red, yellow, orange, pink, purple or greenish sapphire. The Kashmir colour is considered the most sort after sapphire - a pure, intense blue with a very subtle violet undertone, which is intensified yet more by a fine, silky shine. There are a wide range of fancy colours in addition to blue, for example an orange variety with a fine pink undertone called 'padparadscha', which means 'lotus flower'. Star sapphires are another rarity, cabochon cut with a starlike light effect which seems to glide across the surface of the stone when it is moved.Sapphires are found in India, Burma, Ceylon, Thailand, Vietnam, Australia, Brazil and Africa.

Aquamarine since ancient times, has been regarded as the sailors' lucky stone. Its name is derived from the Latin 'aqua' (water) and 'mare' (sea). It is in the same mineral group as emerald but is almost entirely free of inclusions, has good hardness (7.5 to 8 on the Mohs scale) and a wonderful shine. It does not scratch easily and is suitable therefore for everyday wear.  Iron is the substance which gives aquamarine its colour, a colour which ranges from an almost indiscernible pale blue to a strong sea-blue. The more intense the colour of an aquamarine, the more value is put on it. Clear large blue stones with immaculate transparency and magnificent shine are considered the best and some also have a light greenish shimmer. The best large stones are usually from Brazil but other deposits are in Nigeria, Zambia, Madagascar, Mozambique, Afghanistan and Pakistan. Aquamarines are ideal for contemporary unusual cutting due to the large crystal size and lack of inclusions.

Tanzanite is an unusual and rare gemstone because it occurs in only one place worldwide, the East African state of Tanzania, and was only discovered in 1967.Tanzanite is a blue variety of the gemstone zoisite. It consists of calcium aluminium silicate and is not particularly hard, having a value of 6.5 to 7 on the Mohs scale, it also has 'easy cleavage ' in one direction meaning an unlucky knock can cause it to fracture. For that reason, it should always be worn carefully and never placed in an ultrasonic bath. The deep blue of the tanzanite is fantastic, and runs from ultramarine blue to light violet-blue. The most coveted colour is a blue surrounded by a delicate hint of purple. It is thought that all deposits of this gem will be exhausted within twenty years and therefore larger stones can be considered as an investment opportunity. The best stones are often certificated in a similar way to diamonds with 4 colour intensity grades from Vivid to Pale, clarity and cut grades.

Amethyst  has a name derived from the Greek "amethystos", which means "not intoxicated", as in antiquity it was believed to ward off drunkenness. Discoveries of huge Amethyst deposits since the 1800's have made Amethyst fairly inexpensive and very obtainable. Amethyst colours range from light pinkish violet to dark purple, and the transparent deep purple colours are the most highly regarded. It is a variety of Quartz with the colour caused by iron constituents in connection with natural radioactive radiation. It is found worldwide with main deposits found in Brazil, Uraguay and Madagascar.  It has a hardness of 7 on Moh's scale and larger stones often show different areas of colour intensity. Amethyst can change colour when heated or left in strong sunlight.

Citrine is another form of silicon dioxide the same as Amethyst and the yellow colour does occur naturally with the presence of iron.  Historically, it has been found in Spain, on the Scottish island of Arran, in France, Hungary and in several mines worldwide. However most commercial citrines are actually heated treated amethysts. It is sometimes confused with topaz being sometimes mis-named as 'golden topaz'. The colours range from a lemon yellow to gold-brown. A bi-colour form with the purple quartz amethyst is known as Ametrine. The hardness is 7 on Mohs scale and it does not crack easily although it is not a very 'brilliant' gemstone but has a mellow warm tone.  The Quartz group of gemstones is a large one including the leek-green Prasiolite, delicate pink Rose Quartz, colourless Rock Crystal, bluish white/grey Chalcedony , brown-red Cornelian, apple-green Chrysoprase, strpied/spotted Jasper and the Agates.

Zircon comes in a wide range of different colours but for many years the most popular was the colourless variety, which looks more like diamond than any other natural stone because of its brilliance and dispersion. The name probably comes from the Persian word 'zargun', which means 'gold-coloured but the most popular colour is a pastel blue zircon. It is also available in green, dark red, yellow, brown, and orange.  'Hindu poets tell of the Kalpa Tree, the ultimate gift to the gods, a glowing tree covered in gemstone fruit with leaves of zircon. In the middle ages, zircon was said to aid sleep, bring prosperity, and promote honour and wisdom in its owner. Natural zircon today suffers on account of the similarity of its name to cubic zirconia, the laboratory-grown diamond imitation. Zircon is mined in Cambodia, Sri Lanka, Thailand, Myanmar, Australia, and other countries. It is one of the heaviest gemstones with very high brilliance and strong double refraction but is brittle and can chip easily.

Emerald belongs to the beryl group together with aquamarine.The name derives from the Greek Smaragso, which means 'green stone'. Only the finest qualities are transparent. Often the emerald is clouded by inclusions (liquid or gas bubbles, healing cracks and foreign crystals). These are not necessarily classified as faults, but are evidence as the the genuineness of the stone as compared with synthetic and other imitations. The expert refers to these inclusions as a 'Jardin' (garden). The most desired colour is a deep green which is more valuable, even with inclusions, than a pale and clean quality. All emeralds are brittle and combined with internal stress, sensitive to pressure. They can chip on impact, so emeralds should not be worn everyday.
Emeralds should never be cleaned with steam or any cleaning solution that includes ammonia. Most "jewellery cleaner" is not compatible with the oil treatment of Emeralds. To clean Emeralds use warm soapy water and a soft toothbrush. Never use an ultrasonic to clean Emeralds.

Ruby is the red variety of the mineral corundum, of which the sapphire is also a variety, and so is also very hard with good brilliance. Slight traces of elements such as chrome, iron, titanium or vanadium are responsible for the colour. Some rubies display a wonderful silky shine, the so-called 'silk' of the ruby. This phenomenon is caused by very fine needles of rutile. In the rare star rubies it is these crystals that cause a captivating light effect known as asterism creating a six-spoked star.  India was historically the ruby's country of origin and the word 'corundum' is derived from the Sanskrit word 'kuruvinda'. The most prized colour is known as 'Burmese' after the famous deposits in Burma (now Myanmar): a rich, full red with a slightly bluish hue, referred to as 'pigeon-blood red', exceptionally brilliant in natural or artifical light. Those from Thailand are a muted darker brown red 'Siamese colour'.  Some cheaper commercial rubies have been heat treated to improve their colour but has to be disclosed at sale.

Opal is divided into 3 groups: the opalescent precious opals, the yellow-red fire opals and the common opals.The name is derived from an Indian word for "stone". Their physical properties vary considerably. Within the precious opal family there are three types of opal: Doublet, Triplet and Solid.The special characteristics of the precious opals is their opalescence, a rainbow-like iridescence which changes with the angle of observation. Opal always contain water, the content varies but it can be as much as 30%. Over time the stone can loose water, resulting in cracks. To avoid this aging process store opals in cotton wool. The microscopic crystalline structure of opal consists of tiny spheres and therefore the stones are sensitive to pressure and knocks. We advise that opal jewellery is reserved for special occasion wear to avoid damage. To clean opals use warm soapy water with a soft toothbrush or cloth, Doublets and Triplets should never be soaked or immersed in water. Never use an ultrasonic to clean opals. It is advised to avoid extreme temperatures. If unsure on how to clean your opal you are welcome to bring it into the shop

Tourmaline are mixed crystals of aluminium boron silicate with a complex composition, slight differences in which cause completely different colours. Crystals of only a single colour are fairly rare; indeed the same crystal will often display various colours and various nuances of those colours. And the trademark of this gemstone is not only its great wealth of colour, but also its marked dichroism. Depending on the angle from which you look at it, the colour may be different or more or less intense. The name tourmaline comes from the Singhalese words 'tura mali' meaning 'stone with mixed colours', referring to the colour spectrum of this gemstone, which outdoes that of all other precious stones.  A blue /violet colour is sort after and those showing red/pink to green colours are sometimes referred to as 'watermelon'. It is relatively hard wearing,  7 to 7.5 Mohs scale and does not chip or fracture easily. Paraiba tourmalines are the rarest and most valuable type only found a few locations worldwide , one of which is now mined out, the vibrant turquoise blue is caused by copper. Most paraiba available is now from Mosambique.

Garnet is most often encountered in it's deep warm red colour, but also exists in various shades of green 'Demantoid', a gentle to intense yellow 'Grossular' , a fiery orange 'Mandarin' and some fine earth-coloured nuances 'Spessarite' . The deep warm red colours are often described as African garnets and the pinker hues are Rhodolites. The name means 'the grainy one', coming from the Latin 'granum', for grain, referring to the typical roundish shape of the crystals. The garnet gemstone group has similar chemical compositions of aluminium silicate, has 7 to 7.5 Mohs hardness and high brilliance due to a high refractive index. Historically garnet was popular as a talisman and protective stone, as it was believed to light up the night and protect its bearer from evil and disaster. Garnets are found worldwide.

Tsavorite is a green grossularite, a mineral belonging to the colourful gemstone group of the garnets. It was discovered in 1967 in the East-African bushland along the border between Kenya and Tanzania. It is named after the Tsavo National Park, with its abundance of game, and the Tsavo River which flows through it.   It has an extraordinarily beautiful colour and good transparency. The colour range of the tsavorite includes its vivid, radiant green, a springlike light green, an intense blue-green and a deep forest green. It has particularly high refractive index (1.734/44) giving great brilliance. The hardness of  7.5 on Mohs scale and lovely colour make it similar to emerald but without the disadvantage of being likely to crack or splinter as a result of an incautious movement, as with emeralds.  Stones over 2 carats are very rare.

Topaz is a fluorine aluminium silicate and comes in yellow, yellow-brown, honey-yellow, flax, brown, green, blue, light blue, red and pink ... and sometimes it has no colour at all. The most common colour seen is yellow  sometimes called 'precious topaz' to differentiate it from citrine, or pale to intense blue called 'Sky' or 'London' blue (usually heat treated and irradiated colourless topaz). The pink is the most valuable. It has been known for 2000 years and in antiquity was believed to serve in protection against enemies and as a symbol of beauty and splendour. It is very hard, and has good brilliance but with 'perfect cleavage' can fracture with an unlucky blow. Imperial topaz is yellow, pink (rare, if natural) or pink-orange. Brazilian Imperial Topaz can often have a bright yellow to deep golden brown hue, sometimes even violet. In the 18th century a famous mine was in Germany,  now is found worldwide such as US, Cornwall, Australia, Russia, Japan and Mexico

 Kunsite is a delicate pink to violet gemstone named after G.F.Kunz who first described it in 1902, when it was discovered in California. The appeal of this gemstone lies in its clarity and its fine delicate pink nuances which often display a hint of violet. Some kunzites from finds in Afghanistan display a rich, strong violet, a light violet and a light green depending on the angle of observation. In gemmology, this phenomenon is known as pleochroism, the meaning of which equates to 'multi-colouredness'. As a variety of spodumene, kunzite belongs to the class of the chain silicates. It has minute traces of manganese to thank for its fine lilac colour. However, the colour can fade in direct sunlight. For that reason, jewellery with kunzite should never be worn while sunbathing or on the beach. Its hardness is fairly good, between 6.5 and 7 on the Mohs scale, but perfect cleavage and is thus extremely difficult to cut. The more intense the colour, the more valuable the kunzite. Kunzite is said to enhance a person's capacity for devotion and understanding and to bestow inner peace.

Peridot is usually a vivid green with just a hint of gold. It is a very old gemstone found in ancient Egyptian jewellery.The ancient Romans too were fond of this gemstone and esteemed its radiant green shine, which does not change even in artificial light. For that reason they nicknamed it the 'emerald of the evening'. The name is derived from the Greek word 'peridona', which means something like 'to give richness'.In the 1990's a sensationally rich and fine deposit was found in Pakistan, now known as 'Kashmir peridots'. The peridot is one of the few gemstones which come in one colour only. The rich, green colour with the slight tinge of gold is caused by very fine traces of iron. From a chemical point of view, peridot is an iron magnesium silicate. The intensity of the colour depends on the amount of iron actually present. Peridot is not particularly hard - only 6.5 to 7 on the Mohs scale - but it is easy to look after and fairly robust. It is also found in Myanmar, China , Africa and Arizona.

   Birthstones & their Symbolic/Mythological meanings
   January - Garnet : protection from evil & illuminates the night.
   February - Amethyst : intelligence, piety & an antidote to drunkeness !
   March - Aquamarine : marital happiness, joy & wealth.
   April  - Diamond: innocence, eternity & health.
   May - Emerald:  love ,good luck & well-being.
   June - Pearl : peace, nobility & beauty.
   July - Ruby : love, passion & strength
   August - Peridot : success & plenty.
   September - Sapphire : sincerity, loyalty and faithfulness
   October - Opal : healing, true love & an anti-depressant!
   November - Topaz : strength, clear-sightedness & & dispels enchantment!
   December - Zircon : prosperity, honour & wisdom.

Wedding Anniversary Stones
  1. - Freshwater Pearls
  2. - Rose Quartz
  3. - Rock Crystal
  4. - Amethyst
  5. - Turquoise
  6. - Garnet
  7. - Onyx Marble
  8. - Tourmaline
  9. - Lapis Lazuli
 10. - Black Onyx
 11. - Haematite
 12. - Agate
 13. - Malachite
 14. - Opal
 15. - Crystal
 20. - Platinum
 25. - Silver
 30. - Pearl
 35. - Coral or Jade
 40. - Ruby
 45. - Sapphire or Alexandrite
 50. - Gold
 55. - Emerald
 60. - Diamond
 65. - Star sapphire