Many years ago, shortly after I started out, the price of prehnite went shooting up. It was one of those odd things, where I had to do a bit of a double take. What could be going on? I was told, it was because it was being used as a jade substitute for the Chinese market. I did another double take, because I just couldn’t see it. Prehnite is so commonly pale, fractured, full of wisps and veils that I just couldn’t see how it could possibly substitute for jade. And then they brought out the good stuff; deep green, clean and glowing with an unearthly, dreamlike lustre. Ever since, I’ve tried to stock the better stuff, because when prehnite is good, it’s very, very good indeed. You might never even have heard of it. The GIA thinks not, as they have included it in their ‘Hot Gemstones’ round-up, but that makes it an excellent choice as you are not likely to run into it in your local jewellers. It’s a bit different, unusual and the prices (except for the really fine stuff) are pretty sensible. For meaning, it is best known as the stone of unconditional love, said to connect the head to the heart. It’s found mainly in Australia, Canada, China and the USA, and it’s a good choice for anyone who likes their stones untreated as it never is.
I’ve decided to do a series of posts on inclusions, as it is simply one of the most frequent topics that comes up with customers. Everyone knows the value of a nice, clean gemstone: no-one wants a diamond with a dirty great fracture, or a ruby with a big black crystal under the table. However, the search for a perfectly clean stone is a bit of a fool’s errand. The GIA no longer uses the term ‘internally flawless’ to describe diamonds as there is simply no such thing; with increasingly powerful microscopes, if you magnify anything enough times, you will find something. But above all, I think we need to reconsider attitudes to inclusions. The GIA doesn’t call them inclusions; preferring the term ‘clarity characteristics’, and if you believe that the very words we use are instrumental in influencing how people feel about a thing then we can see that this is a much less judgemental term to use. They describe clarity characteristics in a stone as ‘the eyewitnesses to its birth’. They can provide valuable information as to how and where it grew, indicate events in its history and sometimes on a broader scale, in the the events and internal turmoil of earth’s history. They can help detect whether a stone is natural or synthetic and provide evidence as to whether the stone has been treated or not. They almost always tell a story. And if you’ve ever held a pile of synthetic rubies in your hand you might find yourself thinking, as I have, that stones without inclusions can have all the appeal of a piece of coloured glass.
Golden Rutilated Quartz Cabochon Freesize, 41.975 carats, 29.8×21.5×9.6mm, $138.40
Golden Rutilated Quartz Cabochon Freesize, 9.65 carats, 16.1×12.1×7.2mm, $31.85
Inclusions are not always bad, either, and that’s my subject today. Sometimes they have a beneficial effect on a stone’s beauty, and that is certainly the case with needles! Needles are defined as long, thin, solid crystals or hollow tubes; if it’s hollow it might be filled with fluid or gas. A group of fine needles is called ‘silk’. Silk is what gives high quality sapphires their soft, velvety appearance, and can give rise to cat’s eyes and stars, if it is oriented along the stone’s crystal planes. Needles to me are at their best when they are present as visible needles in stones such as quartz and prehnite. These stones are desirable precisely because of their inclusions. In quartz, rutile needles can appear gold, copper, red and black. They can occur sparsely or in clumps; they can be thick and coarse, or they can be fine, the so-called angel-hair variety. You can also get rutilated prehnite; a soft, green bodycolour intersected with striking black needles. When we talk about inclusions it’s easy to see this as always having a negative connotation but it simply isn’t so. Rutilated stones really need only a simple, beautiful setting to show them off to their best, however, I love the setting below, where the design on the body of the ring echoes the spokes of the rutile in the quartz.
To shop our collection of rutilated stones, please click here. Next time I’ll be talking about the dreaded fractures!
When I first started selling gemstones 10 years ago (blimey) one of the first stones that I focussed on was London Blue. It was reasonably priced, plentiful and the colour was like no other. Before I started my journey into gems, blue topaz to me meant swiss blue; bright, vivid cornflower blue. I’m not really a bright and vivid kind of girl (!), or at least, the colours don’t look good on me, so it wasn’t a stone I was interested in selling. London Blue, however was a different story. Prussian blue, petrol blue, I had so many names for this distinctive and elegant shade of greenish blue. No other stone could touch it, except perhaps blue tourmaline (indicolite) but you needed deep pockets for that. And my customers appeared to agree! They couldn’t get enough so I started cutting it in all shapes and sizes. However, around 2015 something unpleasant started to happen; the price started jumping up, the quality began to waver. What could be happening? Well, there two main drivers of this price increase. First of all, let’s be clear. When we are talking about blue topaz we are talking about treated topaz. Blue topaz is irradiated white topaz. It has to be irradiated, and then it has to be cooled – that is, allowed to sit whilst the radiation disperses. The darker the topaz, the longer it has to sit. So whilst sky blue topaz has a 3-month cooling period, London Blue has something like 18 months. There are not many places that treat London Blue, and so that in itself puts a pinch on demand. Added to that you have the increasing popularity of the stone, the unwillingness of suppliers to treat more rough – since it effectively ties up millions of dollars for a year and a half with no return during that time. There is also a natural caution amongst suppliers around the popularity of London Blue. Is the increase just a blip, or is it here to stay? Because it’s one heck of an expensive gamble to treat more rough because it is popular now, only to find that in a year and a half it’s gone out of fashion and they have a whole lot of treated rough that they cannot shift. In my view this wont happen; I think the colour is unique and it has enduring appeal, but I’m not the one having to stump up the cash.
However, this is only half the story, and the woes of London Blue go further back, as so many things do, to the recession of 2008. What happened is very simple; topaz is sourced largely from Brazil, and during this time many mines were forced to close. They have never re-opened and now topaz supply is down by around 60% from pre-2008 levels. For a while there was enough rough in circulation to not have too much of an impact, but this corner was turned in around 2015, when demand began to seriously outstrip supply. So there is now a serious problem in that there are two major pinch-points in the supply chain; a lack of good quality untreated rough coming out of the mines resulting in an increase in price at this point. This has then led to suppliers taking a very conservative attitude towards treating the rough, not wanting to tie up increasing amounts of money in a stone that they fear may be something of a bubble. In reality this seems unlikely. Demand for the stone is still high; it is still a unique colour, and it still is available in clean quality. Although the colour has much more variation than it has in the past, with more greyer, less saturated material on the market some people prefer this, feeling that it looks more natural, more gemmy.
So in short, the outlook for London Blue is that prices aren’t coming down anytime soon. This makes it more expensive to buy, but it also means that it’s unlikely to be a wasted investment. And you could do worse than start here, from top, Ananda Khalsa’s London Blue Topaz ring is set in warm 22 carat gold and sterling silver and highlighted with sparkling diamond dots. I love blue topaz in silver, but putting it in gold takes it to a completely new dimension. I’ve always loved the solid, crafted simplicity of William White’s ring settings; in fact I have a number of stones in my collection I’d love him to set for me. The ring below is a 10mm cabochon in a satin-finished sterling silver band. I do like the angular lines of Eva Dorneys London Blue topaz rings in 9kt gold and sterling silver and I also love the cool stacking system of Barbara S Jewellery. That’s 2 rings, not one; an aquamarine and a London Blue
I do have new stocks of 6mm London Blue topaz cabochons; they are more expensive than I would like them to be but trust me when I say I have shaved the price as low as possible! You can find all of my London Blue here.
Watermelon tourmalines classically mimic the fruit, with their juicy fruit and rind; bright pink in the middle, green on the outside. However, they come in so many different colours, representing the full spectrum of tourmaline’s impressive colour range. In fact tourmaline’s original name was ‘turamali’ which means ‘mixed colours’. It’s quite simply one of my favourite stones, but maybe not the easiest to set; it’s not always easy to find pairs and the profiles are often very uneven and bockety.
Tourmaline grows in pegmatites – veins that run through rocks created by molten magma from volcanoes. As the magma cools, cracks form which fill with a solution of water and minerals such as iron, lithium or manganese. Over thousands of years, these turn into tourmaline crystals, and it is depending on which of these minerals is present that determines the colour. So how do you end up with more than one colour in the same stone? This happens when the trace elements change in concentration or composition during a crystal’s growth. This can result in a core of one colour and bands of different colours, or zones across the length of the crystal. A single tourmaline crystal can contain up to 15 different colours. Tourmaline is the birthstone for October and I always think that is so lucky, as you have such a huge choice of colours. It is said to be particularly beneficial to artists and those in creative fields.
Watermelon tourmaline lends itself wonderfully to carvings – in particular butterfly wings and leaves look great, but arguably the best way to display it is quite simply, in slices, to show off its saturated juiciness to full effect. Although it can be prong-set, I love to see these slices in bezels. I always think of India Mahon as the absolute queen of tourmaline, and I also especially love Sarah Walker’s classic settings below. I haven’t seen slices set like this very often and I really like it. Links and titles on each photo.
I have a range of quality watermelon tourmaline slices, to take a look, click here
Gem treatments have become ubiquitous in recent years. So many stones are treated, heated or fracture-filled; pearls are bleached, jade and turquoise is stabilised. It’s a thing that a some people react against, instinctively put off by the idea of it, as if it detracts from the stone. I’ve often encouraged people to not think of it like that; instead think more of how wood might be waxed or oiled, to bring out its natural beauty. Having said that, not all treatments are equal and we are now at the stage where the gem and jewellery industry has laid down clear guidelines and boundaries as to what is acceptable and what is not. For example, the industry accepts heat treatment of sapphire and ruby, to improve the colour. It accepts fracture filling of emerald, as emerald is such a brittle, fractured stone, whereby the oil filling helps to make the fractures less obvious. It accepts the stabilisation of turquoise whereby these soft stones are infused with wax or resin to make them harder, more durable and better able to take a polish. Certainly untreated stones will always attract a higher price than treated, but these treatments are accepted, as long as they are disclosed. However, there are many treatments that are considered much more controversial, for example the glass filling of rubies and bleaching and dyeing of jade. Anything, really, that results from the taking of very low quality rough and making it appear much, much better than it really is. BE treatment, or beryllium treatment of sapphire is one such treatment, and it has become so ubiquitous in coloured sapphire that many reputable dealers are simply not supplying coloured sapphire.
What is it?
Beryllium treatment is a form of lattice diffusion treatment. Such treatment, previously known as surface diffusion, or bulk diffusion involves the super-heating of pale, colourless, poorly coloured or even dark material in the presence of other elements. Titanium diffused sapphire has been around for a while, and in fact is rather easy to spot. It penetrates only the very surface of the stone and if you look at it under a microscope it is easy to see colour concentrations along facet edges. It’s a problem as it can easily be removed with repolishing. However in the early 2000s, many people began to become concerned at an influx of very intensely coloured sapphires onto the market; mainly in the pink-orange spectrum – stones that were like the very expensive padparadscha sapphires. The stones had been trading for at least 6 months before suspicions began to crystallise enough for serious detective work to begin.
Beryllium treated sapphire, photo GIA, Elizabeth Schrader
Two halves of the same sapphire; the left untreated, the right beryllium treated, photo credit GIA, Elizabeth Schrader
The main problem was that the gem treaters denied strongly that anything new had been introduced. The GIA dedicated a huge amount of time to running their own experiments and concluded that these gems had been heated in the presence of beryllium. The treatment was a form of lattice diffusion, but unlike with titanium diffused stones, the colour penetrates a great deal further and sometimes right through the stones. This makes it much harder to detect. The process introduces yellow, orange and brown components into stones, which results in bright yellow and orange colours from pale corundum, the alteration of pink sapphire to padparadscha, the conversion of bluish ruby to a fine red, and it can also reduce dark tones in blue sapphire to make it a better blue. Initially they faced continuing denial from the gem treaters but through a series of their own experiments they were able to reproduce all of the colours that had been seen and considered suspect on the market. In 2003 the Chanthaburi Gem and Jewelry Association finally admitted to the practice.
Why is it a problem?
The issue is that it taking poor or low quality material and by infusing another chemical and heating to just below the melting point of the stone is considered crossing a line. It goes beyond enhancement as it alters the chemical state of the stone and to put it bluntly, attempts to make a silk purse out of a sow’s ear. What is the problem with that? Well some might say, what’s the issue if the treatment is disclosed? It results in lower-priced stones, and as long as everyone knows what they are getting, what is the problem? The trouble is that the treatment is very hard to detect. It cannot be detected using any standard gemmological treatments and in fact there are only a few gemmological laboratories in the world that can detect the treatment, as it requires a particular kind of laser treatment in order to take samples of the material and test it (LIBS (Laser Induced Breakdown Spectrometer) and LA-ICP-MS (Laser Ablation Inductively Couple Plasma Mass Spectrometer). Labs that do not have the equipment will often state on their reports ‘not LIBS tested’. The issue is not confined therefore to dishonest dealers, but since gems change hands so many times between mine and final customer, information might be lost along the way. You might end up with BE stones without realising it. The person who sold them to you might not realise it. The person who sold them to you might not understand the issues and importance of disclosing it and simply fail to mention it. Someone who doesn’t know much about gemstones might pick up a BE treated stone on their travels, think ‘oh what a bargain’ and then sell it on as if it were not treated, because they simply don’t know that they don’t have a bargain, they have a stone that is worth less than it looks. Once a stone is set, it is hard to evaluate it anyway, and someone who has bought a piece of jewellery may fail to mention it if they sell it on, or give it or bequeath it.
So how do you know?
As I’ve mentioned, it is extremely hard to detect this treatment, and requires specialist gemmological equipment for a definite diagnosis. However, there are indications to the treatment that can be made with standard equipment and a bit of common-sense.
Price: The most obvious one. Pay attention to the standard advice: if it looks too good to be true, it probably is. BE treated sapphires cost a great deal less than untreated stones, so be suspicious of any stones that seem a great deal cheaper than they should be
Colour: BE treatment results in very intense colours. Intense orange and yellow sapphire is very rare in nature so if you are seeing a lot of stones like this, it may be an indication that it is BE treated. This is not definitive as sapphire occurs in all colours, including bright yellow and orange. But if it is natural, it is rare, and it ought therefore to be very expensive. Some reports have estimated that most of the yellow and orange sapphire on the market is now BE treated, so some suppliers (myself included) simply do not touch any of it. Better to be safe than sorry.
Microscope inclusions: with this treatment, corundum is treated to close to its melting point. Normally with heating, you can see evidence in mineral inclusions in the stone, eg halo fractures. With BE treatment, these inclusions will look destroyed; crystal forms turned into irregular masses, often with a crackled appearance and a gas bubble in the centre. This has not been observed with standard heating so it’s a good indication that BE treatment has taken place. You also might see synthetic crystal over-growth on the stone.
‘Rims’ or ‘rinds’ on the stone. You’ll need a liquid called methylene iodide, but if you immerse a BE treated stone in this, you’ll often see a different coloured rim or rind on the stone. However depending on how deeply the beryllium has penetrated the stone, it may not always be obvious. So whilst if you do see it, you can be pretty sure that the stone has been BE treated, its absence does not prove no BE
If you come across any of these indicators, especially if you are buying a large, expensive stone, it is imperative to get a full appraisal from a qualified lab.
Proceed with caution. BE treatment has been implicated in most colours of corundum. Check carefully on the descriptions of all stones you are buying, and ask about BE treatment before buying. I have seen it noted on some websites as ‘Be heated’ under treatment, and no, this is not just rubbish English, it indicates BE treatment. I think it is misleading as I am sure that many people see that and think it indicates simply that the stone is heated. Buying from a large, reputable dealer is important, as even with their small stones that are not worth enough to warrant an individual appraisal report, they will periodically test their rough to check it is not BE treated. I source my stones from such a supplier, and they have told me they stock no coloured sapphire, as so much of it is BE treated, it often comes mixed in with untreated material in the bags of rough, and so to be safe, they do not stock it at all. Although BE treatment has been used for blue sapphire, it is far less common and my supplier has not yet detected it in any of the rough they have bought. For this reason, I will be supplying no coloured sapphire in my store. To shop my range, click here
Actually, the green-eyed monster pretty perfectly describes my feelings whenever I see a piece of tsavorite garnet, whether it’s in jewellery or not. It’s my favourite green stone and I’m sorry, for my money, it beats emerald into a cocked hat. It’s bright green, extremely brilliant and unlike emerald, it’s not routinely treated. Tsavorite garnet, in case you don’t know is the transparent lime-green to emerald green variety of grossular garnet, and actually, the colour is due to the same minerals that colour emeralds – chromium or vanadium. A relative newcomer, it was discovered in the 1960s and is mined in Kenya and Tanzania. It’s hard to find in large sizes, in fact the finest emerald green colour rarely occurs in crystals larger than 2 carats, and so larger stones are therefore a great deal more expensive. Smaller stones are not too expensive, however, and in fact it works really well in pave settings as it is so brilliant.
For centuries, garnet has been thought of as a travellers stone; according to legend Noah’s ark was supposed to have a garnet lantern to help with navigation. In particular, garnet is supposed to promote strength, vitality and positivity, so you really can’t go wrong! We have tsavorite garnet rose cuts in small sizes – 2mm, 3mm and 4mm, starting from $4.25 for a 2mm stone, and I will be listing a few 5mm stones in the next few days. You can browse the collection by clicking here.
This is one of my favourite stones, and the most valuable of the red garnets. Rhodolite garnet has a colour range between pinkish red and deep raspberry pink and it’s not just a colour call that distinguishes it from other red garnets; it is to do with its composition. It’s a mixture of pyrope and almandine garnets, with its own distinctive refractive index, and it tends to come up a bit cleaner than almandine. Although its plentiful and reasonably priced, garnet does generally have a high specific gravity – what does this mean? It means that it’s dense and stones are relatively heavy for their size.
I’m always getting asked about birthstones, and so I finally thought it would make sense to make a section on my website for them. I started off quite ambitiously trying to include every system I could find, but that quickly got a bit complicated and, well, large. So I’ve stuck to modern British and USA systems. There’s a huge choice for every month and I’m looking to boost my selection of precious stones this year, so look out April, May, July and September birthdays! You can browse the selection in my new ‘Shop by Birthstone’ section.
What could I be talking about except garnet! You know what I mean; dull, rusty red stones set in gold-plated filligree. Nope. It’s just not fair. Garnet is one of the most exciting and varied of gemstones. It’s got a very wide colour-palette and price-wise it varies from the highly reasonable almandine to tsavorite at the top-end. It is also the birthstone for January.
Garnet has particular gemmological properties that make it reasonably straightforward to cut – it is what is known as singly refractive so what this means in real terms is that it is not at all pleochroic and therefore cutters don’t have to worry about what angle they are cutting it to make sure they are getting top colour. Many varieties also have a relatively high refractive index. What does this mean? Well, it is a measure of what happens when light hits a stone – a high index means that much of the light is reflected back to your eye; a low index means that much of the light passes right through. In real terms, stones with higher refractive indices are more sparkly. With the darker stones it’s not so obvious, but the sparkle on some tsavorites is simply amazing. See below and bottom for some examples of seriously stylish garnet jewellery.
Ananda Khalsa Garnet Stud Earrings with Two 22k Dots, $440
David J Thomas Tsavorite Garnet and 18k Gold Ring
Coffin and Trout Spessartite Garnet, Rubellite and 18K Gold Pendant
Red is the best-known colour of garnet, and the type that most people think of when they think of garnets is almandine. This commonly comes up very dark, what we call ‘closed’, and especially in larger sizes; however, it can be the most beautiful shade of deep blood-red. I have some almandine pears which just make me think of Sleeping Beauty every time I see them! In fact, the name ‘garnet’ comes from the Latin word ‘granatum’ which means ‘dark red’. Pyrope garnet is also red; you see it more rarely and it often has a slightly pinker note to it – it lacks the rustiness you can sometimes get with almandine. For a more pronounced pink colour there is rhodolite which ranges from pinkish red to a deep raspberry pink. For orange, there is hessonite, with its gorgeous swirling inclusions, and more expensively, spessartite. Malay garnet runs from yellow-orange to a lovely pinkish orange. Then you get the greens; hydrogrossular garnet with its black inclusions, yellowish-green demantoid with its horsetail inclusions, and vivid green, sparkling, firey grossular garnet, more commonly known as tsavorite. This is one of my favourite stones and I would take it over emerald any day. Garnet is also a really good choice for anyone who is not keen on gem treatments as it is not routinely treated with heat or anything else.
Jane Taylor Malay Garnet and 14k Gold Ring, $1200
Vintage Tsavorite Garnet & Diamond Invisible Set Cocktail Ring 14k Gold
Quadram Hexagon Almandine Garnet Ring, $1800
William White Hessonite Garnet and Sterling Silver Ring
Henn of London Spessartite Garnet and 18k Gold Necklace
Pantone has announced their colour of the year for 2019 and it is a bright orange-pink: ‘Living Coral’. From a jewellery perspective it’s a slightly awkward one, as the obvious stone, or rather mineral to represent this colour is, of course, coral. But coral has become a bit contraversial in recent years, due to environmental concerns around the depletion of coral reefs. In the past, red and pink coral was harvested in a completely unsustainable way from reefs in the Pacific, until the coral was all gone. So if you stock it, you want it to be sustainably sourced, but once it is on the market, it is almost impossible to know where it has come from. I’d like to stock this, but I think realistically, it’s not going to be possible. Alternatives in this colour range go from pale to deep orange; I’m thinking peach moonstone, pink pearls, padparadscha sapphire, morganite, conch pearls, fire opal, carnelian, tourmaline and rhodochrosite. I love both La Corser’s conch pearl necklace below paired with the the vibrant yellow diamonds and paraiaba tourmaline, and the softness of William White’s peach moonstone and prehnite combination. From left, clockwise, Turquoise and Sterling Silver Ring, Lia Chahla, Conch Pearl, Diamond and Tourmaline Necklace, La Corser Jewelry, Baroque Pearl Choker, Freshwater Creation, Peach Moonstone, Prehnite and 9k Gold Stacking Rings, William White, and Peach Tourmaline, 18k Gold and Sterling Silver Ring, Janish Jewels.
Turquoise and Sterling Silver Ring, Lia Chahla, $197
Conch Pearl, Diamond and Tourmaline Necklace, La Corser Jewelry, $2060
Peach Moonstone, Prehnite & 9ct Gold Ring, William White, $864
Coloured Pearl Choker, Freshwater Creation, $850
In terms of pairings for living coral, it’s tempting to look to the other brights on their colour report but I think that these will drown this colour. Personally I’m not fond of it paired with bright blues but turquoise and rhodochrosiste can be awfully pretty (see top left and top right). I think it does best when put with more subtle partners. Think peach and white, or peach and grey moonstone. Or as above, peach moonstone with the soft green of prehnite. Or peach pearls matched with white or rainbow moonstone. Or labradorite with any of these, which marries the the soft grey with a turquoise glow.
We have a selection of coral coloured stones; to shop the collection, click here.