Coloured Stones

• Jewellery Information
• Diamonds And The 4 C’s
• Coloured Stones
• Pearl and Opals
• Antique Jewellery
• Watches
• Precious Metals
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Coloured Stones

There are literally hundreds of gemstones and minerals, which have been used in jewellery throughout the ages. The term ‘Coloured Stones’ covers everything from coloured crystalline gems, such as the rarer and expensive colour changing Alexandrite, to the more popular and more accessible Amethyst. In a broader sense, coloured stones encompass many minerals polished or carved for use in jewellery.

Man has been highly inventive over the centuries in using the materials found at hand, and using today’s’ technology can create almost any precious gemstone in laboratory situations.

What makes a gemstone ‘Precious’?

The simplest answer would be a combination of its popularity and rarity.

Today if Pink Sapphire is the ultimate ‘must have’ gemstone, its value increases due to pressures of the world market. Pink Sapphire is not ‘new’, it has simply been ‘rediscovered’, its demand rising as the availability of Pink Diamond is too small for demand.

Of course, there are genuinely rare gemstones, but these too can change in an instant with the discovery of a new mine or source.

Culture also plays a large part. Jadeite, or ‘precious Jade’ is highly prized throughout Asia for its protective and healing properties, and some of the top colours fetch large sums of money. Here in Australia, most think of Jade as the New Zealand variety, which is called Nephrite – or commonly ‘Greenstone’. Neither have a large following in a country which loves the traditional ‘Precious’ stones of Diamond, Ruby, Sapphire and Emerald.

Are Coloured stones graded the same way as Diamonds?

Partly, yes. Each item is examined for its purity of colour, clarity, carat weight and (where applicable) cut.

However, ‘Colour,’ is usually the dominant characteristic, and in general, the deeper and purer the colour the more valuable the stone. There are exceptions though and each Gemstone has its own criteria for excellence.

‘Clarity’  plays a less crucial role, as many gemstones are found in sufficient sizes and quantities to expect the cut gemstone to have few visible inclusions, as those such as Garnets, Amethysts and Citrines for example. There are exceptions of course, as some gemstones such as Emeralds are rarely found without inclusions.

‘Cut’ varies from gemstone to gemstone and usually refers to the shape more than to the perfection of cutting. The Emerald cut for example, is thought to be the best to bring out the richness of colour of its namesake. While in a Pearl, the roundness of the gem is sought.

Diamonds are cut to maximise the light reflective qualities of the stone, whereas a coloured gem is cut to maximise the appearance of the colour. However, well cut stones would still receive a premium over ‘native cuts’ which have been cut without any mathematical consideration!

A unique category for some coloured stones though, is some particular optical characteristics, such as ‘asterism’ in a star Sapphire or Ruby.; this is where the stone is polished en cabochon, and a fine 6-rayed ‘Star’ is visible. Cats-eyes, Schiller and Opalescence are just a few others.

All coloured stones are likewise enhanced, treated and imitated, hence, if you are looking to spend a significant amount of money on a coloured stone, it is best to get advice from a professional jeweller who can guide you through the minefield.

The pricing of coloured gemstones can be a fine art, and knowledge of world markets is essential. Prices will fluctuate due to fashion trends, the discovery of more mineral deposits, the drying up of sources, and worldwide exchange rates. As with diamonds, your significant coloured stones will fluctuate in value over time.

Many gemstones come in a range of colours –Sapphires, Topaz, Tourmalines and Garnets have not only a variety of colours, but can also be found as parti coloured stones, where there is more than one colour within the same stone. Amethyst, Garnet, Citrine and Peridot, are popular stones, often associated with birth dates, and found in most modern jewellery stores.

Then there are the ornamental stones, which are more known for their patterns or specific colouring rather than their rarity. Turquoise, Lapis Lazuli, Onyx and Malachite are some examples.

Finally, please remember that due to all the enhancements available today, it is best to get advice from a professional jeweller who can lead you through the minefield.

Synthetics

A synthetic stone is one that has the same chemical composition and often crystal structure as its natural counterpart, but they are laboratory grown. Today most gemstones are synthesized, from Diamond, Emerald, Sapphire and Rubies, through to Onyx.

Simulants

Simulants are grown in the laboratory also, but are of a differing chemical composition to that of the stone they are intending to simulate. The most well-known and successful is probably the Cubic Zirconia. Although originally designed to simulate Diamond, it is also coloured to look like a variety of coloured gemstones.

Imitations

Imitations refer to pieces that look similar to the precious gem, but are not as valuable. Merchants for centuries have tried to pass Clear Quartz as Diamond, Bone for Ivory and glass for Emeralds, Rubies and Sapphires.

Treatments

Together with the synthesis of natural stones, many ‘treatments’ have come to enhance the beauty of a natural stone. Some treatments are permanent and have been used throughout the centuries, such as heating of gemstones to remove some secondary colouring, Sapphire is an example of this type of treatment as it is difficult indeed to find a Sapphire that has remained unheated once it has been mined.

Some treatments are very hard to detect – such as ‘diffusion coating’, which impregnates a few layers of particles causing the stone to have better colour than in its natural condition. Sometimes these stones would be almost colourless in their natural state.

An important thing to understand is that although you may be happy to own a beautifully coloured stone that has been enhanced chemically or by radiation, you should still be ‘informed’. Most treatments should be declared at point of sale, and the price should not be compared to what may be a similar poorer coloured natural stone which is valued higher because it is completely un-enhanced.

The list of treatment is extensive, therefore, we will advise you on the most utilised treatments in the marketplace today along with a brief explanation of what they are.

By law, all of the above treatments should be declared at the time of sale.