Tag Archive | treatments

Turquoise, the friendship gem

The sun is out and we’ve been breaking out our summer jewellery, one of the most fabulous summer jewels is turquoise which might seem a strange choice, but it’s an excellent summer stone as the bright colour gives a great fresh look to nearly every outfit and faux turquoise jewellery is frequently found on the high street during the summer season (ok we admit it’s also a great choice in winter too – amazing contrast against black and in fairness it is December’s birthstone, so let’s agree that it’s an all round jewel).

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Turquoise is an opaque gem which has been valued by people for thousands of years due to its colouring.  It can be traced back as far as the Ancient Egyptians and Aztecs and is thought to have been introduced to Europe through Turkey, and it’s believed that this is how it was given its name.  Given it’s age there’s no surprise that myths and beliefs surround this gem, in ancient times it was thought that it could have some prophylactic uses (!) and that it changed colour to reflect the health of the wearer.  Whilst it’s true that Turquoise does turn green with dehydration and chemical reactions or treatments can change the colour even more,  as far as we know this doesn’t actually link to the wearer’s health…  Turquoise has also at times been believed to protect the wearer, and  has been used as both a talisman and holy stone.

Double Headed Serpent Turquoise Mosaic, the British Museum Collection

Double Headed Serpent Turquoise Mosaic, the British Museum Collection

What is clear is wherever you go in the world you are likely to spot a fair amount of Turquoise in their museum pieces, turquoise was often inlaid into both jewellery as well as building decoration, bridles, swords to name but a few.  Turquoise was even found in Tutankhamun’s tomb in his burial mask amongst other items, and famously examples can be found in the British Museum such as Aztec death masks.

Turquoise Mask, the Turquoise Mosaics collection, the British Museum

Turquoise Mask, the Turquoise Mosaics collection, the British Museum

Much admired, but often under appreciated in modern society, Turquoise has been much copied throughout the ages.  It’s fairly surprising that it has stuck around so long, particularly preserved ancient pieces, as it’s not one of the more durable gems.  Even the best turquoise is fracturable and on the Mohs scale it’s just under 6 at it’s hardest, similar to glass.  It’s also a porous gem and can be affected by reactions with other chemicals.

Turquoise is generally known as a fairly low value gem in today’s society, due to the prevalence of fakes or synthetics, and variety of available treatments means that it can be hard to tell what is real and what is not.  This uncertainty affects the price, as does the large influx to the market that synthetics bring.  However, this has not always been the case and it used to be held in high esteem by the Apaches of North America.  It was thought of as a particularly useful gem giving authority, protection and if given (rather than bought) can bring good luck (particularly on a Saturday…) and preserve friendship.

Examples of our own Turquoise are below, despite it’s structure and nature it can be faceted, it also takes a great polish and there are some simply stunning examples of cabochon cut Turquoise.  One of our favourite Turquoise pieces at the moment is this gorgeous Astley Clarke friendship bracelet.

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Turquoise has distinguishing inclusions caused by other minerals and metals being within the gem, but rarely it can be found without these, which is known as sleeping beauty turquoise.

Treatments

There are lots of treatments which can be applied to turquoise, and it is often treated to enhance its durability as in its natural state it is not particularly hard and suffers from being highly porous.  Other treatments are used to change the colour of the gem and there are some great examples particularly of purple turquoise.  Be warned if you are bothered about your turquoise being treated, whilst a gemmologist may be able to test to ascertain they type and occurrence of treatment, such tests are likely to damage your stone.

Some of the more basic treatments are waxing and oiling turquoise which enhances the colour and lustre of the gem, whilst these add to the appearance of the stone it can result in some discolouration over time if the stones are exposed to too much heat or sun.

Some turquoise is “stabilised” by having resin or plastic inserted into the stone under high pressure, this treatment is more stable than wax or oil so has better long-term results and can lead to otherwise unusable turquoise being brought up to gem quality.

Other treatments are more radical, such as reconstitution or “block” turquoise which is formed by bonding small fragments of turquoise with resin, or gluing thin turquoise onto another material to reinforce it which is known as “backing”.

Care

Whilst it’s important to take care of all your gems, the nature of turquoise, even when treated, means that chemicals such as oils, perfume or sun cream could lead to discolouration or damage of your stone.  The gem can dehydrate so try to keep away from strong sunlight for prolonged periods and store in a breathable material.  Due to it’s softer nature it’s also preferable to keep your turquoise away from items that could scratch it so a special section of your jewellery box or a pouch is a good idea to try and protect it.  Also bear in mind that it can’t be cleaned with the majority of jewellery cleaners, so when you take it off try giving it a gentle rub with a lint free cloth to keep it looking at its best.

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The colour of love?

As it’s July we thought we should do a quick shout out for July’s birthstone today (particularly as one of us is a July baby!)

Ruby spray

Ruby is a gem quality variety of corundum, and is essentially a red variety of sapphire.  Fine rubies are actually rare as they are formed when a soft limestone rock was put under extreme heat and pressure within the Earth’s crust, but more than that the limestone then had to come into contact with just the right elements, including chromium, which makes them relatively rare.

Due to the way they are formed all natural rubies have imperfections which include colour differences or markings, and silk, although this silk is an imperfection it is important to enable natural rubies to be distinguished from synthetic rubies.

Rubies reach 9 on the Mohs scale, which

The majority of us will identify a ruby simply because it’s red, but there’s actually more to this gem’s colour than simply one word.  As they are part of the sapphire family different countries take a different approach to colour identification, for example in the United States a minimum colour saturation must be met before a “ruby” becomes a ruby rather than a pink sapphire.  The ICA takes a more liberal approach, but it’s something you should certainly turn your mind to the issue of colour.

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 True or false?

Synthetic rubies are relatively common and were first created in 1937, by 1910 the annual production of synthetic rubies had reached 1000kg.  The fewer imperfections in a ruby the more likely it is to be treated with suspicion and identified as synthetic.  In addition to its use in gemstone jewellery synthetic ruby has use in industry as they can be used to make lasers or other production where it’s hard nature is useful.

What is interesting is that in addition to having to detect synthetic rubies, a number of imitation rubies are often found in the form of glass, or the genuine gemstones such as garnet and spinel.  The confusion between ruby and other gems has been a long standing issue, sometimes not helped by the use of some trade names such as rubellite, but one of the most famous examples of this confusion can even be found in the Crown Jewels!  A stunningly large spinel can be found on the Imperial State Crown, known as the Black Prince’s Ruby.

Myth & Legend

Back in time, as with many precious stones, people used to believe that ruby had powers to preserve the health of the wearer.  Particularly ruby was seen to help the wearer by changing colour when danger was close at hand, protect from poison and plague and even make the wearer invulnerable to steel weapons.  Ruby is absolutely surrounded by acres of legend, particularly stemming from the reverence it was given in South East Asia. and it’s definitely worth a read as some of the stories are interesting.  Star rubies were even more highly prized, it was believed that the star was formed by three benign spirits which had been imprisoned in the stone for a misdemeanour, the spirits represent faith, hope and destiny and it is thought that this type of stone can bring good fortune to the wearer.

Treatments

Due to their nature and the naturally occurring imperfections the overwhelming majority of rubies are treated before coming to the jewellery market.  The most common treatment is heating, but other treatments include colour alteration, fracture filling or dissolving silk defects within the ruby.  Heating can improve both the colour and silk within the ruby.  Fracture filling does what it says on the tin, essentially using lead glass (or similar translucent) to fill the cracks within the ruby, which improves the translucency.

Unlike with some gems the treatment can be observed through a 10x loupe, and the majority of treatments are acceptable due to the nature of natural ruby.

Ruby pendant

If you do manage to find a natural, high quality, untreated ruby then snap it up as they are extremely rare!  However you should be warned that you will need deep pockets (far beyond our own means sadly) to keep hold of it!

 

All the “C”s

So whilst it’s lovely to gaze over diamonds and dream, what happens when you want to purchase?  It’s pretty well known that the things to look for in a diamond are the C’s i.e. colour, clarity, carat weight and cut, but what does this mean in reality and is this really all there is to it? 

Diamond grading

 

Colour

Basically the less colour visible the higher the price (except for fancy coloured stones, but again more on coloured diamonds later).  You will mostly come across the GIA grading system which uses a letter system of colour grading. D being the highest grading of colourless, descending towards Z travelling through near colourless, faint yellow, light yellow and so on.  At the very basic level as the colour and grade increases the price of your stone decreases.

 

Black diamond

Clarity

Clarity is defined as the degree to which a stone is free from external marks (called blemishes) and internal features (called inclusions). Like with colour the freer the stone is from blemishes and inclusions the more expensive the price tends to be. These factors, like with colour, are given grades; the GIA clarity grades start at F1 “flawless, no blemishes or inclusions” which are very rare and expensive (essentially, “we wish”).  Diamonds are generally found in high street jewellery around lower grades such as SI1 & SI2 which are slightly included, ranging from easy to see under 10x magnification (i.e. using your loupe) and somewhat easy to see with your naked eye. Diamond grades end at I1-I3 (P1 -P3 is used in some countries) which are imperfect, characteristics and flaws which can be seen easily with the naked eye.

 

D grade diamond ring

Carat

The unit of weight used for diamonds is the carat, in most cases the higher the carat weight the higher the price, a carat is a unit of weight equalling 1/5 of a gram. The weight of small diamonds are often expressed in points, with one point equalling 0.01 ct (carat) Diamond jewellery in stores may often have the total diamond weight on display which for example 1ct for a 5 stone ring will not therefore be of an equivalent value as a 1ct single stone in a ring. Also take note if the quantity is expressed in points or carats, as 0.25 points is not equivalent to 0.25 ct which is a quarter of a carat.

Cut

This refers to the proportions and finish of the stone, two of the main considerations of cut are:

  • Do you see brilliance all across the stone when you look through the stone face up? You should not see large dark areas.
  • Are you paying for excess weight? is the stone too fat basically when you look at it sideways a poorly cut stone may have a very thick appearance from the side but look much smaller from the top this will also effect the brilliance that stones gives off. Symmetry is also a consideration as this also affects the level of brilliance emitted by the stone.

Cut can be judged by the naked eye and a 10-power magnifier, but it is not as simple as it sounds (naturally!)  Cut should be considered in more detail, looking at the cutting style and quality and the shape of the stone.  The finish is also important as how well the cut is finished can affect sparkle and brilliance.

Whilst cut is very much about personal taste trends affect prices so at the moment round stones tend to cost more than pear, marquise and emerald cuts but this hasn’t always been the case.

Normally square shapes cost less than round as there is less wastage when the stone is being cut from its rough state, and there is usually less demand for squares. However, depending on demand in different areas of the world princess cuts (squares) have occasionally sold for more than rounds.

 

Heart facet

Anything else…?

Well in short…yes!  (Sorry this is turning into a long post but we promise this is only scratching the surface, hard to do on a diamond!)  Transparency is another factor to consider, the degree to which the stone is clear, hazy or cloudy as again this will alter how the stone reacts to light and therefore how it looks when being worn.

The other thing to take care of when dealing with diamonds is the treatment status i.e. whether the stone has had any external treatment since being mined.  There are a number of techniques and treatments which have been developed to improve the look of white diamonds; some have been deliberate attempts to deceive buyers but with a reputable jeweller you should be able to ask about any treatments of the stone.  An example is the process of using a laser to vaporize black inclusions, this leaves a fine white thread that starts at the surface and travels into the stone.  This treatment is permitted but must be disclosed on any certificate obtained.  Fractures and cracks can be filled with a glasslike substance that is visible only under magnification.  Certain types of yellow-tinted diamonds are put through a high-temperature, high-pressure treatment (HPHT) process to make them colourless. This treatment is permanent and heat treated diamonds can only be identified in a lab.

Depending on what you’re after in a gem treatments are not necessarily something to shy away from, they can reduce the value of a stone but give you the look of a much better quality stone.  One of the things you should beware of though when it comes to treatments (not only in diamonds) is that not all treatments are permanent, the filler we have mentioned above is not a permanent treatment and bad care or handling can loosen the filler or change its colour.

 

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