Parti Sapphires
Colour is a key variable in sapphires. Along with clarity, it is arguably the most significant factor in coloured gemstones. In the world of sapphires, blue has remained the most dominant colour: to a point where the colour that is instinctively associated with the sapphire stones around the world is a rich blue hue. However, sapphires today come in an array of different colours. Gems in this range also vary in terms of specific tones that correspond to greater or lesser levels of vividity and tint.
The science of colour aside, what we going to discuss today is the parti sapphire. Which is another unique addition to the corundum gemstone family. Before we get into it, here is a quick hint: it shares a visual similarity with the disco ball. Hence its name.
What are Parti Sapphires
Parti sapphires are corundum gemstones: meaning they are like any other blue sapphire or any other sapphire gemstone in this family: in that, they share the same mineral character, and like other coloured sapphires (white sapphires are technically colourless) they derive their colour from the presence of trace minerals.
What sets parti sapphires apart is their distinct colour or colours! As the image above indicates parti sapphires unlike conventional stones in this family, feature two or more colours. Which makes them, use the technical term bi-coloured sapphires. In parti sapphires, the dominant hues are a combination of deep green, yellow, and shades of blue. All three hues vary in terms of concentration, and their presence depends on the gemstone in question.
Before we get to the technicalities of what makes parti sapphires what they are, it is important to note that the prevalence of two more hues in a single corundum stone does not mean the gemstone in question is a parti sapphire. As they are sapphire variants that feature two distinct hues in the same stone. However, the key difference lies in how the colour is present in the stone. In parti sapphires, the two or sometimes three main hues appear to be concentrated on two sides of the stone with other areas featuring lighter tones, with the middle section appearing to showcase lighter hues. In addition to the glowing admixture of these three colours across the stone is akin to a form of stained glass effect.
Thus parti sapphires are sometimes referred to as polychrome sapphires owing to the presence of not just the two or three main hues but the multitude of shades that are spread across the gem.
Where Do Parti Sapphires come From
Historically the souring of parti sapphires has been from Australia. Over the decades Australia has developed a growing reputation of being an emerging player in the sapphire industry, one that has been dominated by the likes of Ceylon, Thailand and Myanmar. Whilst the traditional blue sapphires are still primarily sourced from these nations, along with new sapphire-producing nations in Africa, Australia has developed a reputation for being the home of parti sapphires.
Australian Parti Sapphires
The prominence of this variety of sapphires has given rise to the perception that parti sapphires are typically Australian and that these sapphire variants are only from this part of this world. Not so. Parti sapphires are sourced from a few other countries. However, it is worth mentioning the prominence of Australian parti sapphires is not misplaced. Since Australia was once (going back a few decades) one of the most prominent sapphire mining nations in the world. Built on its traditional mining and natural resource prowess. Whilst its dominance in sapphires has waned over time, it has established a dominant position in the parti sapphire range. Australian parti sapphires are most abundant in the market today, with strong yellow shades.
Parti Sapphires from Kenya
In the past decade or so the Continent of Africa has produced several top sapphire-producing nations. Notable among these are nations like Mozambique, Tanzania, and Madagascar. Kenya as a sapphire-producing nation is well known, but it has been able to produce a distinct variant of parti sapphire. Kenyan parti sapphires, unlike the Australian types, come with stronger green hues, and given their distinct tones are considered to be among the most valued in the market.
Parti Sapphire from Montana
Montana sapphires are sapphires mined in the North Western United States, which has become a new source of sapphires and other precious stones. The parti sapphire variant from this region is known for its varied combination of hues, that go beyond the traditional green and yellow combinations, and incorporate new hues like lighter versions of blue, yellow and tinges of green, and even variations of purple, creating a kaleidoscope of glittering hues in a single stone. Of course, such Montana parti sapphires are a bit harder to come by. But it is worth noting that parti sapphires from the US and other gemstones are among the most ethical.
Distinct Features of Parti Sapphires
A question that many readers may have when it comes to parti sapphires is what makes them so? What set of factors makes parti sapphire feature multiple hues in a single stone. Here it is important to understand the chemistry of the stone. Colour in sapphires, as in most gemstones is a function of its trace mineral character. Parti sapphires feature a combination of iron and titanium in various minute amounts that give to their colour. Affects the stone's ability to interact with light, in terms of what specific wavelengths are absorbed and to what extent.
The Role of Color Zoning
Since colouring in sapphires, in their rough uncut state, tend to concentrate in certain areas, which gives rise to the specific dominant colour in a gemstone: such as blue, green or purple. The concentration of colour in certain areas is a phenomenon that is a feature of most sapphire varieties. Parti sapphires feature more than colour in a single gemstone but differ in that the different colours remain distinct within the same stone. The question is how do these differences emerge? The answer is that it is a result of a phenomenon called colour zoning: where certain parts of the gemstone are effectively cordoned off, preventing the overlap or merger of colours that make the parti sapphire different from the dual colour effect. One way to understand the difference is to look at teal-coloured sapphire: which features pretty much the same hues as the parti sapphire but unlike this variant, the colours appear as an admixture, spread across the stone.
For what sets these gemstones apart is not just the presence of dual hues or more in a single stone that produces the ‘disco ball’ effect. Rather it is how these colours are dispersed throughout the stone and the distinct glittering effect they produce when they come into contact with light. However, to produce such glittering multi-colour effects comes down to the quality of the gemstone’s cut. As jewellers, when it comes to coloured stones like sapphires place a premium on the coloured regions of the stone, and with experts, cutting can bring about the distinct hues in a single stone.
Choosing Parti Sapphire for Jewellery
When it comes to choosing a parti sapphire for your jewel, such as an engagement ring, several factors need to consider. First the authenticity of the stone. Since the market for multicoloured gemstones is an evolving one, with a lack of information when it comes to gemstone identification, determining its country of origin and cut quality, customers need to pay close attention to the gemstone’s country of origin, the quality of its about its carat, and the quality of its colour.
Note that it is not good enough for a parti sapphire to simply have the parti sapphire, multicoloured effect. Good quality parti sapphires must feature the parti sapphire effect in addition to having a richer tone, that showcases the colours of the gem. Thus parti sapphires which are darker and featured multicoloured effects are not a good choice for fine jewellery.