Purple Gemstones

jodiegearingStone Knowledge

I love working with coloured gemstones, and a colour that never seems to go out of fashion is purple. Less obviously girly than pink, purple is a beautifully wearable colour in any season. There is a vast choice when looking for a purple stone. Here follows some information about some of them to help you decide which is right for you!

Tanzanite

The colour of Tanzanite ranges from blue to blue-purple to blue-violet. It is a pleochroic stone, which means that when viewed from different angles, the colour can change.

Tanzanite is a trade name that was first used by Tiffany and Co. for gem-quality specimens of the mineral Zoisite with a blue colour. The world’s only known Tanzanite deposit of commercial importance is found in northern Tanzania, hence the name choice.

Most of the popular gemstones have been used for hundreds of years, if not longer, but Tanzanite was not discovered until the 1960s. It is now the second most popular blue-toned stone after Sapphire.

Mohs scale of hardness

Tanzanite has a hardness of about 6.5 on the Mohs Hardness Scale (compared to diamond at 10, the hardest gemstone). 6.5 is low enough that the gem is a little vulnerable to being scratched, or the facets rounding off during normal wear (particularly if it is set in a ring). Hardness is something to be taken into account when designing a piece of jewellery with Tanzanite; those set in rings should be set in such a way that the edges are protected, e.g., a bezel setting. Pendants and earrings can still suit more delicate designs, such as the claw setting we used on this pendant –

You can read more about this commission here.

Price

As Tanzanite is currently only found in one region, this keeps the price high. As these deposits dwindle, we may see the price skyrocket. Tanzanite is at least 1000 times more scarce than diamond, but due to the price of diamonds being strictly controlled, they are still usually more expensive than Tanzanite.

As with most gemstones, pieces of Tanzanite of any size are rarer than smaller pieces, so larger gemstones are proportionately more expensive than smaller ones (meaning that a 2ct stone will cost more than double of that weighing 1ct).

The colour and clarity of a Tanzanite will significantly affect the cost. The deeper the colour and the clearer the stone, the more it will be worth. Tanzanite tends to be a fairly clear stone, so any inclusions should bring the price down considerably.

Ideal cuts

Oval and cushion cuts are the most popular for Tanzanites, but they also work well in trillion and round cuts. A long and pointed shape like a Marquise cut would not work so well in Tanzanite as the slimmer points will appear lighter in colour than the deeper centre of the stone.

Tanzanites can often be found in unusual and custom shapes rather than the standard shape cuts we see in other gemstones. This is to achieve the best colour from each sample of stone. Tanzanites tend to be cut deeper than other gemstones to help achieve these deeper tones, so when sourcing a Tanzanite, check with your jewellery designer to make sure the stone is well-cut. You are looking for a symmetrical stone that is not cut so deep the light does not reflect well.

Interesting facts

Tanzanite is one of December’s birthstones, along with blue Zircon.

 

Amethyst

Amethyst is the purple variety of the quartz mineral species and is the gemstone most commonly associated with the colour purple. The colour can range from pale lilac to a deep and intense royal purple, or even a pinkish hue known as ‘raspberry.’ Amethyst also commonly shows what is called ‘colour zoning,’ which usually consists of angular zones of darker to lighter colour.

An interesting variety of amethyst is the stone called Ametrine. This is where the stone has formed in bands with the yellow quartz known as Citrine. The end result is a beautiful combination featuring the contrasting colours purple and yellow, usually cut in elongated shapes such as oval cuts, with one end purple and the other yellow.

Mohs scale of hardness

Amethyst measures at about 7 on the Mohs scale of hardness, making it tough enough for any kind of jewellery.

Price

Amethyst is a surprisingly affordable stone, as even fine amethyst examples have a modest price tag. Large gems remain affordable as the price per carat does not rise dramatically with larger size stones. This is because large geodes are commonly found – some big enough that you can stand inside them!

Amethyst was as expensive as ruby and emerald until the 19th Century, which was large deposits were found in Brazil. Today, as the most valued quartz variety, amethyst is in demand for designer pieces and mass-market jewellery alike, and its purple to pastel hues retain wide consumer appeal.

Where they originate from

Amethyst is found abundantly in Brazil, where it occurs in large geodes within volcanic rocks. It is also found and mined in South Korea, but it’s Austria that houses the largest opencast amethyst vein in the world. Much fine amethyst comes from Russia, but it can also be found in south India, southern Africa, and across the USA.

Ideal cuts

Amethyst works well in any calibrated cut, making it an incredibly versatile stone. I recommend sourcing a range of stones from which to select your favourite in the flesh.

One of my very first jewellery commissions was this silver and amethyst pendant designed for Liz by her husband for their 25th wedding anniversary. Her birthstone and favourite gemstone is amethyst, so we sourced this incredible deep, royal purple briolette as the centrepiece to this unusual design. You can read more about this commission here.

Interesting facts

St Valentine, the patron of romantic love, wore an amethyst ring carved with the image of Cupid. It is the birthstone for February babies and the Anniversary gemstone for 6th and 17th wedding anniversaries. Amethyst is the official state gemstone of South Carolina, US.

 

Purple Sapphire

Image credit: thenaturalsapphirecompany.com

Sapphires are one of my favourite stones, in part because of their durability and, therefore, excellent suitability for a range of jewellery, but mostly I love them for their variety. So much so, that I have to hold myself back for the purposes of this article. I will write a post focused entirely on Sapphires in the future to share my love for his magnificent stone, and will, for now, just give you the highlights.

When you say Sapphire, most people automatically think ‘blue,’ which is the standard colour you’ll see in high street jeweller’s displays. However, sapphires actually form clear, and the minerals around them as they develop determine the colour they end up being. Sapphires come in all colours of the rainbow (except red – more on that later) and even different shades of each colour. In terms of purple sapphires, these can come from pale lilacs to deep and intense royal purples.

Mohs scale of hardness

When looking at the hardness of Sapphires, they come a close second to diamonds (10) at 9. This means they suit being in any type of jewellery and will take a fair amount of wear and tear. However, I have seen some examples of very old Sapphires where the facet edges have worn and rounded over time. This, of course, can also happen to diamonds, as all gemstones will wear with age. Any piece of jewellery should be removed if you are doing something that could cause damage.

Price

The cost of a sapphire varies depending a lot on the colour and quality. Particularly rare colours (such as Padparadscha – an orange/pink colour) will be more valuable than more commonly seen tones. They are more affordable than diamonds but are still considered a precious gemstone and therefore carry a price tag to match the title. As with any gemstones, I recommend sourcing a range of different stones to choose from in the flesh. A ‘better’ stone on paper may not have as much life as one further down the quality pecking order, and this cannot be quantified.

Where they originate from

Commercial mining locations for Sapphire include (but are not limited to) Afghanistan, Australia, Burma, Cambodia, China, Colombia, India, Madagascar, Africa, Sri Lanka, Tanzania, Thailand, and the USA.

Ideal cuts

Sapphires suit all sorts of cuts. They are often cut with a brilliant pattern on the crown, and a stepped cut on the pavillion to best suit their properties.

Interesting facts

Sapphires and Rubies are the two stones of the corundum family, meaning that these two heavyweights of the gemstone world are, in fact, the same type of stone. Rubies are essentially red Sapphires. Sapphires are the birthstone for September babies.

 

Alexandrite

Image credit: minerals.net

Often described as ’emerald by day, ruby by night,’ Alexandrite is the very rare colour-change variety of the mineral chrysoberyl. Its colour turns from a lovely minty green in daylight or fluorescent light, changing to purplish-red in the incandescent light from a lamp or candle flame. This is a result of the complex way the mineral absorbs light.

Mohs scale of hardness

Alexandrite has a hardness of 8.5 on the Mohs scale, so it is a very durable gem and suitable for all types of settings and jewellery.

Price

Most cut Alexandrite weigh less than one carat. Larger, higher-quality gems rise in price dramatically due to their scarcity.

Where they originate from

In 1830, Alexandrite was first discovered in Russia’s Ural Mountains. It is now also found in Sri Lanka, East Africa, and Brazil, but fine material is exceptionally rare and valuable.

Ideal cuts

Alexandrite is most often available in mixed cuts. Its rarity means it is usually cut to save weight, so it can be found in some unusual and non-standard cuts. The most important thing to do is to check that the stone is cut symmetrically and has a good refraction of light to achieve a lively sparkle.

This ring was made as a family birthstone piece as a gift for a lucky lady’s big birthday. The Alexandrite in this piece is not the purple stone to the right of the central ruby, but is the minty green stone to the left the centre. I deliberately placed the stones in this order as depending on the light, the central ruby would be flanked by two purple stones (one Alexandite, one Amethyst).

Interesting facts

Alexandrite is a birthstone for June, along with pearl and moonstone. Alexandrite is also the gem for the 55th wedding anniversary. This interesting stone was named after Czar Alexander II, who emancipated Russia’s serfs and was assassinated in 1881.

 

Other purple gemstones

Other options for purple gemstones include Spinel, Iolite, Fluorite, Topaz, Kunzite, Zircon, Diamond, Tourmaline, and Garnet. It is worth taking a look at them all to find one in a shade you love, at a cost you can work with.

Hopefully, this insight into these four gemstones has been helpful, but I’d love to hear which is your favourite, or if you think I have missed one that should be celebrated.