At JDS we have 2 Gemmologists who are also qualified Registered Valuers on staff, which means they have not only trained over many years, they are required by law to maintain their credentials with ongoing training. They will provide you with information on any of the coloured stones, and advise you on any treatments that may be involved, and how that may impact on the long term wear of your piece.

The designers love coloured stone design, because they offer greater design choices as they are, in many cases, less prohibitive in cost, allowing for larger and bolder stones to be used.

What makes a stone precious?

Usually it comes down to popularity and rarity.

Rarity reflects the availability (or lack of) the gemstone in the market place. For example, tanzanite is a stunning purple blue colour stone named by Tiffany & Co. in the early 1900’s and our newest birthstone. However the single mine source means resources are slowly dwindling, and there is an expectation the mines will dry up in the late 2020’s.

Diamonds on the other hand are not really a rare gemstone, certainly quality white stones and some of the rarer colours such as pink & blue diamonds are, however there are new diamond mines still being explored, and old ones which continue to produce after decades of service. Diamonds are the most sought after gemstones in the world – not just for jewellery, but due to its hardness for mining, medical, space and other industries, so pressure is placed on the market value of the stones.

Culture can also play a part. Jadeite or ‘precious jade’ is highly prized throughout Asia for its protective and healing qualities, parents buy for their babies to wear at an early age, and top quality stones would rival some diamonds in value. In Australia we tend to think of jade as the ‘nephrite jade’ or ‘greenstone’ that is highly popular in New Zealand. The value is lower as it is more abundant, and the demand is also lower.

In Australia, our national gemstone is opal. Few locals appreciate the value of this unique stone as much as those overseas. However Opal mines are drying up, and our bountiful resource is winding down. Prices of top stones are increasing steadily.

Are coloured gemstones graded the same way as diamonds?

To some degree they are. As Registered Valuers we assess each stone in a similar way to the 4 C’s of diamonds.

Carat – Cut – Clarity and Colour.

However in gemstones, importance falls more heavily on colour, as the attractiveness of the colour is what we look for most. In general  the darker and purer the colour the more precious the stone.

Many stones mined overseas have poor cut, but this does not affect the optical value of a pretty coloured stone in the same way as it affects a diamond, where a poor cut can produce a very sad and uninteresting looking stone despite its colour and clarity.

Clarity is generally less crucial, depending on how available the stone is, and the size of the crystal, stones such as citrine, amethyst and several of the garnets are available as nice clean stones. Other stones such as emerald are rarely found without inclusions of some type.  This can be interesting in itself as most emeralds can actually be pinpointed not only to country of origin but also mine sites. A feat that is extremely difficult with most other stones including diamonds!

With the cut of a stone, in general a good cut will enhance a gemstone that has a good even body colour, however many are cut shallower or deeper to ensure that maximum colour is visible through the top. Cut has more variety in coloured stones, with cabochons and carved stones being added to the list of standards

A fifth category can be applied to many coloured stones, and that is their optical characteristic.
For example, several stones including rubies and sapphires exhibit ‘asterism’ when cut en cabochon. This means a light reflection is permanently visible showing a ‘moving star’ effect. Cats eyes in chrysoberyl, schiller in moonstone, and fire in opal are a few examples of optical effects that can enhance a gemstone's value.

Are coloured stones a good investment?

There are many coloured stone specimens, both as cut stones and as crystals that are extremely rare and very valuable. These are for the experienced and specialist investor.

Traditionally we have viewed sapphires, rubies and emeralds as being the most prized of gemstones and the most popular, however their long term value is dependant on their quality and history. Some gemstones will be regarded as extremely rare, only in the next moment to reduce in value as another location has been discovered, so in general it is a speculative area of investment

We must always remember that many of these gemstones have taken hundreds of thousands of years to form, and whilst we continue to improve search techniques and rework old sites, they are not being replaced at the same pace. It is important to conduct detailed research if the intention of purchase is for investment purposes. Our trained staff are happy to assist with any questions.

Synthetics, created stones, colour enhancement…

Synthetics

A synthetic stone is one that has the same chemical composition and crystal structure as its natural counterpart, giving it the same physical properties, but they are ‘grown’ in a laboratory. In the stores they will be classed generally as ‘created’ stones. The list of ‘created’ stones is too numerous to list here, but generally assume that any stone available has a synthetic counterpart.

Please be aware that there are incidences of ‘synthetic’ stones being sold direct from mine sites around the world. There have been cases where they have apparently been dug out of the ground in front of potential buyers, having been secreted there by canny locals earlier in the day! Certainly apply the term ‘buyer beware’ when purchasing stones from locals overseas. In many cases these created stones can only be identified by professional gemmologists.

Imitations

An imitation implies a stone that is sold or created for the purpose of imitating its natural counterpart. This has occurred for hundreds of years. Coloured glass imitations (or paste) have been used for hundreds of years to imitate sapphires, rubies and emeralds, and so although a stone may have been passed through the family it is not necessarily natural. Other examples are bone used to imitate ivory, plastic for pearls, jades and corals.

Simulants

A simulant is a stone ‘created’ in a laboratory in order to mimic a natural gemstone. The most well known of these would be the cubic zirconia used to imitate diamond. It does not necessarily have the same characteristics as the natural stone,  but visually looks the part.

Treatments

Colour enhancement  has been traditionally used for hundreds of years. Some stones such as sapphires are heated to remove very fine inclusions in the stone and the colour becomes more even. This is considered an acceptable treatment in gemstones as the effects are permanent.
However we now see more and more gemstones where coloured outer coatings are added to make them appear brighter and more expensive. Unfortunately the coating does wear off returning the stone to its original less attractive state.