A guide to bi-colour sapphires
This guide to bi-colour sapphires will introduce you to the distinctive gems that feature two or more colours within a single stone. Also known as ‘parti coloured’, we delve into how bi-colour sapphires are created, what makes them special, and how to choose the perfect one for you.
What is a bi-colour sapphire?
Known for their dazzling colour, many people associate sapphires with rich shades of blue and indigo, like the sapphire made famous by Princess Diana’s iconic engagement ring. But did you know that sapphires come in virtually every colour imaginable? From black to orange, with yellow, purple, peach, pink, green and every shade in between.
The technical bit
The science behind these precious stones allows nature to serve them up in a variety of ways. Beyond that, there are even sapphires that contain a multitude of colours throughout the stone.
Bi-colour sapphires (also known as parti coloured sapphires) are gemstones that feature two or more distinct colours within a single stone. These precious gems are always one-of-a-kind due to their organically produced colour. This is a unique, naturally occurring phenomenon that shows just how much of an artist mother nature can be.
What colours do we get?
Similarly to diamonds, regular sapphires can be either grown in a lab or form naturally in the earth over millions of years. The difference with bi-colour sapphires is that they can’t be produced synthetically and only occur naturally.
And how does a sapphire get its colour, you might ask. Classed as a precious gemstone, sapphires are part of the corundum mineral family, meaning they’re composed of aluminium oxide, iron, titanium, chromium, copper and magnesium. That’s a mouthful. When combined under the immense pressure of the Earth’s crust, these metals and minerals compress into sapphires. The colour of a sapphire is determined by subtle variations in the amount of each element found in and around the gemstone.
For example, a yellow sapphire is caused by high amounts of iron within the stone. More iron than titanium will create a green corundum stone, while more titanium than iron will give a sapphire a blue shade. Still following?
The location of these different elements as well as the changing composition of the surrounding deposits and stone over millennia is what creates the alternating tones within bi-colour sapphires.
Parti colour sapphires are judged based on their ‘colour zoning’ (the location of the different colours), the colours’ contrast with each other, and their respective saturation. This spectacular variety is what makes parti sapphires such an exciting choice for an engagement ring: they’re as unique as the love story that inspired the ring in the first place.
Bi-colour sapphires are much more rare than single toned sapphires as they only occur within a perfect storm of geological conditions that can’t yet be replicated in a lab.
That being said, bi-colour sapphires tend to occur anywhere natural sapphires are found, although in some locations more than others. Australia is really well known the for its abundance of bi-colour sapphires, and many teal and blue-green bi-colours come from the ancient riverbeds of Montana, USA. At Taylor & Hart, we source most of our parti sapphires from the famous Ratnapura region of Sri Lanka. You can read more about our incredible team in Sri Lanka and their sapphire expertise here.
The most common colour pairing amongst bi-colours is green and yellow. Sometimes the two colours will evenly split within a stone, and sometimes they are marbled together like a tortoiseshell motif. The rarest combinations are those that contain powder blue, cornflower blue, or purple shades. Some stones have been known to exhibit pink, orange or silver tones as well, and these are especially desirable because of their sunset-like tonality.
Bi-colour sapphires are actually highly valued by collectors for their rarity and distinctive appearance. Their unique colouration makes each stone truly one-of-a-kind, adding an element of exclusivity and intrigue to jewellery pieces they appear in. The enchanting effect of colour zoning in these stones often gives them a magical, almost otherworldly quality that captivates people around the globe.
Is a bi-colour sapphire a good choice for an engagement ring?
The short answer: absolutely.
But despite their dreamy, one-of-a-kind appearance, bi-colour sapphires remain relatively unknown, thus, quite uncommon. However, the popularity of coloured gemstones has been on the rise, making them one of the top engagement ring trends of 2020. Could this golden age of colourful wedding jewellery finally allow bi-colour sapphires to take centre stage?
Sapphires are an incredibly durable gemstone, making them ideal for everyday wear. In fact, sapphires score a 9 on the Mohs mineral hardness scale (a measure of the resistance of materials against scratches of harder materials), meaning they’re second only to diamonds in terms of durability. You can be confident that your parti sapphire engagement ring will last a lifetime.
When choosing a bi-colour sapphire it’s best to work with a gemstone expert or jewellery designer in order to find a stone with the most suitable cut for your design, along with the best colour pattern. Another interesting thing about bi-colour sapphires is that they’re commonly cut in artistic and creative shapes—more so than their single tone counterparts. This is because a cutter will study a rough bi-colour sapphire’s colour pattern and cut the stone to best feature the colours rather than retaining the most carat weight.
Looking to create a custom bi-colour sapphire engagement ring? Get in touch with our team of design specialists who can help you find your dream gemstone and talk you through all the ins and outs of making a personalised coloured gemstone ring.
