4C’s + 1C = 5C’s – Evaluation of Sapphires
Just as with other gemstones, the carat weight, clarity, cut, and colour have significant control over how a sapphire appears and its quality. We want to share some experience about the 4C’s for sapphires. When determining and buying a sapphire the most important aspects to consider are not only the standard 4C’s but also another important factor namely the country of origin of the gemstone, so for us it is 5C’s.
Unlike the universal grading system used to value diamonds, around 70% of a coloured gemstone’s value is based on its colour. Colour gemstones of the same carat weight are valued very differently depending on their colour, but it is an interplay of all aspects for determining quality, attractiveness and the intrinsic value today and predict future value development.
A gemstone’s size, if expressed in a unit of weight, is called a carat or abbreviated “ct”. A carat is a metric unit equivalent to one fifth of a gram. The carat weight of sapphires does not necessarily define the value of the stone but in general per carat prices increase with overall carat weight of the stone. The effect of carat weight upon sapphire value varies from colour to colour. Yellow sapphires are comparatively plentiful in sizes above five carats, but five-carat padparadscha sapphires are extremely hard to come by.
Large sapphires are many times rarer than smaller sapphires, meaning carat prices increase disproportionately – a five carat sapphire is worth many times more than five one Carat sapphires of a comparable quality. Prices for sapphires increase more exponentially or sometimes step-wise when in excess of certain significant carat weights. Expect steep increases in the price per carat at the one, three, five, and ten-carat levels. Fine blue, pink, orange, or padparadscha sapphires that exceed fifteen carats are especially valuable and can fetch very high prices at auction.
Colour interpretation is unique from one person to the next. Lighting may also affect the appearance of colour. We always do our best to give our sapphires the most accurate colour classifications and the resulting colour description is based on our professional opinion. For years, gemologists have sought a more universal and objective means of assessing colour in sapphires. As a result, the colour quality of a sapphire depends on three parameters; gemstone’s hue, tone and saturation. These parameters are used in conjunction to determine colour quality of a sapphire.
Hue is the gemstone’s basic colour. While a sapphire’s colour might be described as yellow or blue, more often gems are a combination of hues e.g. violetish-blue or greenish-blue. Tone, which describes how light or dark a stone’s colour is, will also influence a sapphire’s value. Saturation describes how pure or intense a colour appears, and it is a key component in determining a sapphire’s value. Regardless of the sapphire’s hue, higher levels of saturation are preferred, which means modifiers do not dilute their colour. The finest sapphires have “vivid” saturation, but sapphires with “strong” saturation are also prized.
In terms of blue sapphires a velvety to violetish blue sapphire hue with a strong saturation without compromising the brightness, in medium to medium dark tones can command a higher value. It is still a matter of taste, changes in favour exist between cultural areas. From a price perspective cornflower blue, vivid blue and royal blue sapphires are more expensive, then lighter pastel or really dark blue colours. However in Europe the demand for lighter pastel-blue and a medium water-blue with an excellent luster and fire are increasing especially for younger people as well as fancy colours like pink, purple, yellow, orange in all colour shades from light to intense.
A number of other factors may also contribute to the apparent colour of a sapphire. For example, certain inclusions or minute needles of rutile silk can actually improve the colour of a sapphire. A sapphire’s colour may also depend on how it is cut. Skilled gemstone cutters maximize their brilliance, minimize colour zoning, and exhibit their best pleochroic colour. One final aspect for evaluating gemstone’s colour is the lighting. Sapphires generally look best viewed with fluorescent light or daylight, particularly around just after sunrise and before sunset. Incandescent lights, whose output is tilted towards the red end of the spectrum, do not do most blue sapphires justice. Take also into account daylight differences around the world, in particular strong saturated blue sapphires appear around 10-15% darker in European daylight to its appearance under Sri Lankan daylight.
The presence of inclusions and trace minerals create the unique colour and overall look of each coloured gemstone. As a result, each sapphire is truly unique and no two will ever be the same or have the exact same internal structure. Clarity refers to the imperfections visible inside a sapphire. Typical imperfections in a sapphire include inclusions, feathers, silk, cavities or colour zoning. The placement, size and quantity of the imperfections are of the greatest importance matter. Inclusions can affect the sapphire’s beauty and brilliance in both ways positively in terms of colour and negatively in terms of clear visibility on the surface however inclusions are always considered an unmistakable natural feature.
A perfect eye-clean sapphire does not exist, every eye of the beholder is different to judge this generally. However almost eye-clean sapphires are extremely rare and valuable, especially when even the finest gemstones are not expected to be free of inclusions even when viewed under magnification. It is important to accept that there is and can be no uniform system of clarity grading for coloured gemstones worldwide. Even though a clarity level is often stated for gemstones, it is subjective and not very serious from our point of view. While diamonds are valued for their lack of inclusions, all of gemstones are expected to have a certain amount of inclusions as a result of their natural crystal growth.
When evaluating clarity for a sapphire, the grading of “very slightly included” or “slightly included” is more reliable then “eye-clean” as the optimal clarity, meaning no bigger inclusions are visible to the naked eye. Unlike diamonds, gemstones are graded without any tool or magnification to make clarity judgments. Reliable for the assessment of clarity, the sapphires are viewed at a distance of about 10-15 centimeters and the different viewing angles by tilting them to visually check whether any inclusions are visible to the eye on top.
The term “cut” can have several meanings when applied to gemstones, e.g. the faceting style, shape of a finished gemstone or gemstone’s proportion and finish. Proportion refers to the rough dimensions and overall symmetry of a gemstone. Finish describes the precision with which facets meet, the relative size and number of facets, and the quality of the stone’s polish.
With precise and skilled cutting the brilliance and beautiful colour of the sapphire will reveal itself. A well-cut and well-balanced sapphire is going to determine whether or not it sparkles, displays flaws, or exhibits its ideal colour. So one needs to consider the overall quality of the cut when making some jewellery. Cut shall not be misunderstood with shape.
A cutter evaluates the rough sapphire stone to determine the ultimate shape and size of the gem. Orienting the cut to achieve the desirable colour is the final goal of the cutter. In general deep cut sapphires preserve weight and show off more colour whereas shallow cut sapphires appear bigger for their weight and look lighter than the deep cut ones. However, the rough stone determines how it will be cut, depending on the colour centre or colour point, the depth of the sapphire can therefore vary and is determined by nature.
Faceted sapphires are found in a variety of shapes and styles. While oval shapes are most commonly seen as most rough stones have an ideal rounded shape for this, but of course other shapes such as round (brilliant or step cut), cushion, pear, marquise, baguette and heart shape can be found as well. Slight premiums are levied upon emerald, asscher, princess, octagon, hexagon or any fancy-cut sapphires due to the higher carat weight loss of more expensive and bigger rough sapphires during cutting.
Unlike the industry norm of cutting for maximum weight retention, our manufacturing quality ensures that each stone leaving the factory has been cut to exact mathematical parameters, ensuring uniform weights in whatever diameter size required. This gives an added advantage to our jewellery manufacturer customers who are now able to cost finished jewellery pieces with greater accuracy. This also allows their design teams the freedom to now realistically conceptualize and create pieces previously thought impractical as they can be confident of the uniformity of each individual stone that we supply.
Country of Origin
Sapphire from all countries of origin, whether from Sri Lanka, Kashmir, Burma, Thailand, Africa or Australia and the USA, all have the same chemical composition, they are all belong to the mineral corundum. The difference lies in the geological conditions in which they were created, various trace elements have shaped them during their formation and therefore there are differences in the qualities. Quality characteristics like colour and saturation, brilliance or liveliness. The shape of the rough stones, colour criteria as well as the examination of inclusions and the respective growth structures within the mineral provide information about the country of origin of a sapphire.
The origin of the sapphire has a considerable influence on the value of the coloured gemstone. The market pays by far the highest prices for sapphires from Kashmir, followed by Myanmar (Burma) and Sri Lanka (Ceylon) at comparable levels with a clear premium over all other countries with sapphire deposits. This has something to do with the rarity of the deposits at first, but of course also with the quality characteristics. New sapphire deposits such as those in Madagascar almost 10 years ago or in Thailand is the exception rather than the rule; worldwide production volumes are declining significantly, especially in the mining regions that are known worldwide for the finest qualities.
Over hundred years ago Kashmir sapphires occurred in Northern India in the Himalayas at an elevation of nearly 15,000 feet since then the small deposits are exhausted. The extreme rarity of this valuable gemstone surrounds them with an almost mythical allure. Verified historic Kashmir sapphires can sell for astronomical prices. Kashmir stones set the standard for evaluating blue sapphires. They have a velvety texture and their colours tend towards slightly purplish blue, with strong to vivid saturation and medium to medium-dark tone. While some Burmese and Ceylonese sapphires come relatively close in quality.
Burma is known as the finest deposit of rubies in the world and also produces beautiful, intense blue sapphires of finest quality. The sapphire deposits are small, as there is no state-regulated mining there and it has always been a region of conflict. The typical Burmese sapphire colour is slightly violet blue, highly saturated and medium to medium dark tone.
Ceylon produces the finest quality sapphire that is available in the market today. The sapphires come in a light blue to dark blue, where the darker the colour, the finer the sapphire is. There is very rarely a Ceylon stone that is considered too dark, unlike a Thai, Australian or African Sapphire. Ceylon sapphires have a true cobalt blue colour, unlike an Australian or Thai sapphire that has more of a black-blue colour. Because Ceylon sapphires tend to be on the lighter side of the colour spectrum, they are generally cut deeper in order to bring out the saturation of colour. The most supplied blue sapphires from Sri Lanka range from a typical medium water-blue to cornflower blue or vivid blue. Royal blue sapphires do exist, but in terms of volume they are rarer but more lively in appearance and of higher quality and value than comparable sapphires from Madagascar or Thailand.
However in Sri Lanka, sapphires in every colour except green and blue-green or teal can be found from medium to vivid and strong saturation and in light, medium or medium-dark tone. For every taste and every budget from very rare to simply beautiful. Most blue sapphires on the market tend to show slightly grayish to violet-blue hues, in a light to medium tone and the full range of saturation mostly medium to vivid. However, their occurrence has also declined significantly in the last 10 years, which has led to a doubling of market prices and this can be predicted to continue in the future as the worldwide demand for fine Ceylon sapphires is unbroken.
Therefore one can summarize sapphire pricing, like that of nearly all other gems, is subject to a “non-linear-scale of increments” and its value reflect the rareness of a natural product of nature. For gemstones there is no one universal grading system to grade a sapphire. Respectable gemmological institutions have developed their own grading schemes to rate the overall quality. The American, Swiss and German gem labs are of a high international reputation and leading worldwide standards, therefore one should only rely on experienced and trustful long-term orientated business partners. Always ask about the source of each gem, way of processing, quality management and documentation of a traceable supply chain as well as invest in a gemstones report for valuable gems.
Natural corundums often are treated for optimization. Untreated gems are rare, and hence of an even higher value. The use of heat treatment is very common for sapphires. It is a standard process, but customers should be educated about the background and difference. Most natural sapphire and ruby have their colour enhanced or deepened as well as improving their clarity through heat treatment at high (up to 1.900°C). Without this practice, we would see far less sapphires on the market with similar good clarity or colour, and at far higher carat prices due to limited supply, hence making sapphires more accessible and affordable. The proportion of unheated sapphires on the market is small and is widely thought to be in the range of 1-2% depending on different references. Natural, untreated corundums without heading have a prefix “no indications of heating” or “NH”. The prices per carat (pcts) are significantly higher for untreated corundums because they are rare and face an even higher price development over time, especially for larger carat weights above three, five or even ten carat. Although they are no more beautiful, but their rarity makes them highly collectable and prices are set at a premium, sometimes fetching triple the price paid for an equivalent heated sapphire.
Through our exceptional network we have access to unheated sapphires and real rarities. All other forms of treatments (chemical optimization, irradiation, oiling, dying, surface diffusion, etc.) we entirely reject because we stand for the natural unaffected beauty of Ceylon sapphires and gems.