Diamonds & Precious Stone information
Diamond Quality Grading
In the order of importance: cut, colour, clarity and carat (the four Cs)
Cut
The Cut grade refers to a diamond's ability to return light (sparkle). Even with exceptional colour and clarity when a diamond is poorly cut, it will look dull. When choosing a diamond the cut needs to be considered as important as clarity and colour. The diamond's cut determines its fire and brilliance. The cut grade is established by defining the relationship between a diamond's light performance, dimensions, and finish.
Cut
The Cut grade refers to a diamond's ability to return light (sparkle). Even with exceptional colour and clarity when a diamond is poorly cut, it will look dull. When choosing a diamond the cut needs to be considered as important as clarity and colour. The diamond's cut determines its fire and brilliance. The cut grade is established by defining the relationship between a diamond's light performance, dimensions, and finish.
Shallow cut:
If a diamond is cut too shallow, light escapes out the back of the diamond and its fire and brilliance is diminished.
If a diamond is cut too shallow, light escapes out the back of the diamond and its fire and brilliance is diminished.
Good, very good, or ideal:
.These qualities of cut allow the minimum of light to be lost. The majority of light that enters the table (flat top of the stone) is being reflected back though the table. Enabling the stone to show its best fire and brilliance.
.These qualities of cut allow the minimum of light to be lost. The majority of light that enters the table (flat top of the stone) is being reflected back though the table. Enabling the stone to show its best fire and brilliance.
Deep Cut:
If a diamond is cut too deep, light will escape out the side and as with the shallow cut fire and brilliance is lost.
If a diamond is cut too deep, light will escape out the side and as with the shallow cut fire and brilliance is lost.
Light Performance; the overall appearance of a diamond when it is viewed from the top.
The description factors in the brightness, fire and scintillation of the diamond in both fixed and tilted positions.
In order to cut a good, very good, or ideal stone the diamond cutter needs to have a high level of skill and experience. The higher grades of cut also take longer to achieve. Therefor diamonds with the highest cut grades cost more.
The description factors in the brightness, fire and scintillation of the diamond in both fixed and tilted positions.
In order to cut a good, very good, or ideal stone the diamond cutter needs to have a high level of skill and experience. The higher grades of cut also take longer to achieve. Therefor diamonds with the highest cut grades cost more.
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Colour
The presence or absence of colour is the basis for grading in diamonds. With traditional white Diamonds the less colour visible in the actual stone material the better the grade (how white is the diamond). The whiter the stone the more of a rainbow flash will be seen, showing a more colourful fire. A diamond with a gadding of D, E, or F is regarded as colourless. Offering good value Colour grades of G, H, I, and J are near-colourless, A colour grade of D is the highest possible, while Z is the lowest. |
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Colour shows itself in a diamond as a pale yellow. This yellow is not strong enough in tone to be considered a coloured stone and has a dulling effect on the stone (in coloured diamonds the intensity of colour enhances the diamond). Because of this a white diamond's colour grade is based on its lack of colour. The less colour a diamond has, the higher its colour grade.
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After cut, colour is generally considered the second most important characteristic when selecting a diamond.This is because the human eye tends to detect a diamond's sparkle (light performance) first, and colour second. The visible difference between diamonds of one colour grade, for example G to H or I to J, is so minor it is difficult to detect with the unaided eye. The difference in price however, can be significant.
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Clarity
Clarity is a measure of the number and size of the tiny imperfections that occur in almost all diamonds. Flawless clarity diamonds are rare and expensive. A diamond with flaws that can’t be seen by the naked eye, (referred to as eye-clean) can be good value. The beauty that is seen by the naked eye when viewing the eye-clean diamond is usually not affected by these imperfections because they are microscopic. Much is made of a diamond's clarity, however many experts agree it has the least impact, in terms of the 4Cs on a diamond's appearance. These imperfections are referred to in technical terms as blemishes and inclusions. Diamonds with the least and smallest imperfections receive the highest clarity grades. |
Carat Weight
Carat is a measurement of weight and not size. Therefore two diamonds of the same carat weight but differently cut, when viewed from the top, may or may not appear to be the same size. Every carat is divided into 100 points (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 a number of thresholds in the per-carat price of diamonds. They are caused by the fact that the rough (the uncut crystal) for the heavier diamond is rarer than the rough for smaller stone. As the diamond weight increases the price per-carat rises exponentially. Also to be taken in to account is the clarity and colour. The better quality stones are also rarer. There are weight thresholds where the price per carat jumps. A 90-point stone may be more than 10% cheaper than a 1 carat stone because of a price threshold. The one carat stone being more popular creates a price threshold. It is the demand for the one carat stone that creates this particular price threshold not the availability of the two different stone weights. 
The difference in the look of the size of the two stones may be difficult to see when viewed from above. Generally, it can take around about a 20% increase in carat weight for the size difference to be obvious.
Because of these price thresholds a 1 carat stone will be more than double the price of a half-carat stone (which is also called 50points). A 1 carat stone is a lot more valuable than one hundred one point stones. Two common diamond threshold price jumps are at the full-carat and half-carat marks. To get the best value, look for diamonds just below these sizes, for example purchase a .97-carat diamond instead of a one-carat. Visually, you will not be able to see a difference in size, but your savings may be significant. Many shops advertise a ring having a total of one carat of diamonds made up of smaller stones. There is nothing wrong with this as long as it is understood that the small stones adding up to a carat are not as valuable as a single one carat stone. |
Fluorescence
Fluorescence is the reaction of trace minerals within the diamond that cause the diamond to glow when exposed to ultraviolet light. Ultraviolet light is the light that is often used in night clubs to give the effect of making white things glow. Sunlight contains ultraviolet light (as well as other light wavelengths) so diamonds with fluorescence will react to daylight. About one third of all diamonds fluoresce. More than 95% of those that do fluoresce will fluoresce blue. The next most common color is yellow. Fluorescence grading is: None, Negligible, Faint, Medium, Strong, Very strong. Diamond valuers agree that fluorescence that is yellow has a negative impact on the look of a diamond, and it value. However the impact of blue fluorescence on diamonds is debatable. It has been commonly believed, that diamonds with colorless grades (D-E-F) or near colorless grades (G-H-I-J) appearance is negatively affected by fluorescence lowering their value. However the faint yellow grades (K-L-M) tend to be higher in price when exhibiting fluorescence, the blue in the fluorescence improving the perceived colour of the diamond and counteracting some of the yellow. 
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From agate to diamonds, stones created by the earth are beautiful and fascinating, encompassing all the colours of the rainbow.
What to Look for in Coloured StonesWhen 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. |
Cut
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 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 can 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.
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When choosing between different coloured stones it can be helpful to know that stones have different specific gravity's. 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.
Looking for a particular stone? We will do our best to source it for you.
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If you are a collector of gemstones, or wanting to display a stone in jewellery, we could have what you are looking for. We have a range of precious, semi-precious, and specimen gemstones, as well as some fossils.
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