Gemstone treatments have been around for a very long time and, being a bit of a purist, I used to think that all treatments were evil things out to deceive. I think I'm slowly changing my mind, at least in part. If you know where you stand, what's the problem.
In November I attended a seminar in London by the "Masterchef of Gemstones", Ted Themelis. If you can heat a Ruby or Sapphire in a particular way to get a different effect, he'll know how. When I attended this seminar I knew we would be covering many aspects from the traditional treatments such as heating, which has been performed for centuries to lighten or darken colours, sometimes producing a different colour altogether, as well as remove some characteristics, through to the bang up to date, "add a bit of this and a bit of that" types, some of which can even start to alter what you would call a particular gemstone. I am really trying not to make this too heavy, but it is tricky.
In his seminar, Ted pointed out that not all treatments are bad as long as you know what you're dealing with. He's right of course. I was recently offered a collection of untreated rubies at more affordable prices than those you see come up in auctions such as Sotheby's and such like. Most members of the public wouldn't have recognised them as Rubies. The colour was a subdued pinkish red, there were obvious black inclusions in the stones (you can't just scrap them if they have inclusions of this size due to the limited quantity of stronger colour material, untreated material) and they were cut in a way to maximise the weight as wasting this untreated material to get a more pleasing shape loses money. Compared to the heat treated Rubies I handle every day, they were awful.........but rarer.
To give an example. In an untreated Ruby, I could offer you a stone 4mm round with a very dark inclusion, almost black, on one side of a very pinkish red stone. I could also offer you an oval 5x7mm rich orangy red heat treated Ruby with a colour rich enough to hide all but the most dark inclusions. These two examples are the same price. In a shop window the two stones would look totally different and most people wouldn't recognise the untreated stone as a Ruby. I doubt that I could sell the round one.
We do get people coming in and asking for untreated stones because they are "as nature intended". If it was as nature intended we would being selling crystal that have been un-cut, "as nature intended". Not that this would bother me as first and foremost, I am a mineralogist, and find the vast array of crystal forms and oddities fascinating and beautiful. Lets just pause on that thought, "as nature intended", if this applied to everything in our lives, how boring would it be? Most fabrics are not brightly coloured and need dying. You would only be able to eat apples from late summer to winter and the prospect of no synthetic materials, plastics and things is just to scary for me to deal with!
Back to what Ted was talking about. Some treatments are a bit more scary. Diffusion treatments, where another substance of chemical is packed around gems and some of this chemically bonds with the gem altering its colour whilst being heated. Not so nice. A fair number of countries in the world are obliged to tell you of this treatment (disclosure) but not all. Surface or sub-surface diffusion produces a skin of intense colour that does not penetrate the whole stone (normally, see later). Think of a watermelon, red inside with a green skin. A yellow Sapphire could be colourless in the middle but a bright yellow "skin" covers the outside making it look yellow. I was told that this treatment can now go as deep as 2.5mm into the stone. On a 3mm round stone that means all the way through! Not a great treatment, but if you have a good looking colour that hasn't cost much and you know its treated wheres the harm? Just make sure if it gets scratched over time and needs re-polishing, the jewellers knows what it is as it will save a heart attack. You can just imagine someone polishing the stone and noticing the colour getting lighter and the colorless as the layer of treated stone gets ground away!
Really scary now. Flux or glass filled. Sometimes stones have cracks an fissures that need fixing. If you heat up a stone, Rubies are the most common to receive this, with certain chemicals, they melt a bit and start filling the cracks. The most common material used at the moment is a lead "glass" PbO lead oxide. To start with the stone can look great, but its short lived. Over time the glass will get eaffected by abrasion, chemicals and even lemon juice. If one of these goes in an ultrasonic cleaner that jewellers use after an hour it will degrade a lot, and this is cumulative six, ten minute blasts will have the same result. They are even now producing "composites" of Ruby and glass. Think of it as making a biscuit base for a cheesecake. Crushed or bits of biscuit (ruby) stuck together with butter (glass). Not good and should be very cheap.
Many countries in the world are obliged to tell you what something is, if its treated and how. Many countries don't, hence I spend a lot of my time breaking the bad news to people when they've bought things on holiday. Ted summed it up in one little example at the end of the seminar, which I've expanded on.
If you come into my shop looking for a Ruby I will tell you its weight, its heat treated its a natural (produced by nature) Ruby. £1000 is the asking price.
In many countries, they place a red stone in front of you and £1000 is the asking price. Is it treated? Whats the weight? Is it man made? And even. Is it a Ruby?
Nature does a great job, but we don't always appreciate it, hence treatments. This brings affordable stones to the masses, but the important thing is, knowing where you are. If its treated, pay a treated price and accept it.
P.S. If anyone has a few pictures I could use to liven this up, please get in touch.
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