What to Look for in Coloured Stones
When looking for coloured stones, there are a large variety to choose from. Pearls, to emeralds, sapphires, and opals to mention just a few. We are happy to discuss with you all the different features of the particular stone you are interested in. However there are some fundamental aspects to look for in many precious and semi precious stones.
How well the stone has been cut holds the most influence over the stones beauty. It will affect the rainbow spectral flashes of colour caused by the refraction of light that has entered the stone though the top of the stone (the table) and exits though the table, giving the stone is sparkly look. This is called dispersion. You may find two stones of the same size and quality but one seems a lot cheaper than other. Some stones that have been cut quickly and cheaply to keep the price down could attract the unaware bargain hunter. It is difficult to judge the dispersion of a stone purely by looking at a photo. The true life and colour of a stone needs to be seen in person for it to be truly appreciated.
Colour: Look for an intense and attractive colour, generally not too pale or too dark.
Purity: The degree of foreign material in the stone. A small amount is acceptable. Over a certain amount will degrade the stones value.
Clarity: Flaws in the stone. Flawless coloured gemstones are rarer than flawless diamonds. Though clarity is important it does not carry the same premium as it does in diamonds. Inclusions naturally occur in gemstones and distinguish a natural stone from a synthetic.
Large inclusions may interfere with the passage of light though the stone reducing its brightness (the dispersion of light or how sparkly the stone is).
When a client is interested in one of our stones, we have a microscope available to examine any stone they may be considering.
Emeralds are an exception when talking about clarity. Their value lies in the intensity of their colour, as they almost always have large and/or many inclusions (flaws).
When looking at stones in a jewellery shop the stone/s may appear misty (lack of any sparkle). This can be a sign of a poor quality stone, also an indication of a cheaper stone. The stone may have impurities and be badly cut.
Size: There are 100 points to a carat (just as there are 100 cents to the dollar). However, stones jump up dramatically in value (price per carat) as they increase in size. There are size thresholds where the price per carat jumps (different types of stones have different size price thresholds). A 90-point stone may be noticeably cheaper than a 1carat stone because of a price threshold. The difference in the look of the size of the two stones may not be that obvious when viewed from the top. A 1carat stone will be more than double the price of a half-carat stone according to the price thresholds. A 1 carat stone is a lot more valuable than 1 carat of 1 point stones.
When choosing between different coloured stones it can be helpful to know that stones have different specific gravities. Therefore an amethyst with specific gravity of 2.65 will look bigger than a sapphire with a specific gravity of 3.90-4.00 the sapphire being a denser material assuming the stones are of the same weight and cut. We come across examples of this in our day-to-day life. For example, a Kilo of lettuce will have more volume than a Kilo of apples.
A larger stone with a flaw may be preferred to a smaller perfect stone that would cost more. This also applies to the colour of the stone. It is purely a matter of personal taste.
Buy from a reputable point of sale. Gems have a more or less established price according to their quality at a given point of time. Relentless search for a bargain may lead buyers to less scrupulous dealers. If you feel you must buy a stone off the internet be aware that it is very hard to tell what a stone really looks like from a photo. Always buy from an Australian dealer, as Australian consumer laws will protect you. Ask for a receipt that identifies the type of stone you are buying and its weight. This should not be a problem for a reputable jeweller or dealer and it gives the customer security.