If you’re into sapphires you might already know they come in different colors, and some colors are considered more precious than others, the same way the origin of a sapphire matters. So what about Montana sapphires ? Where do they fit in, and just how precious are they ? Are they any different from Burmese or Ceylon sapphires ? Do they have specific color or clarity ? Let’s take a look !
What is a Montana sapphire ?
Montana sapphires are those sapphires mined exclusively in Montana state, USA. Of these sapphires the most famous are the Yogo sapphires, mined in the Yogo Gulch in the state of Montana. Sapphires from this state come in any color, but the most famous are the Yogos which are a blue-green shade. They’re often eye-clean, which is unusual for sapphires, hence why most Montana or Yogo sapphires are not heat treated.
Montana sapphires are a national pride, and are the root cause of modern sapphire certificates stating whether the stone was treated in any way for color and/or clarity.
Is it Montana or Yogo sapphire ?
The term Montana sapphire applies to all sapphires mined within the state of Montana, while Yogo sapphires are only those mined in the Yogo Gulch, Montana. So all Yogo sapphries are Montana sapphires, but not all Montana sapphires are Yogo sapphires. That being said, many blue sapphires mined in Montana are labeled as Yogo sapphires, because their blue-teal color is like the blue-teal of actual Yogo sapphires. Here’s a more detailed explanation.
Montana sapphires can be any color, Yogos are blue/teal
Montana sapphires come in all colors, blue, pink, white, green, teal, yellow, and some very rare cases of rubies. Meanwhile the sapphires mined in the Yogo Gulch are almost always blue, though they often have a slight green undertone, making them teal in some lighting.
So not all blue/teal Montana sapphires are from the Yogo Gulch, but most of them are. That being said, you’ll often find Yogo sapphires sold as ‘Montana sapphires’, and people have been referring to them as Yogo or Montana interchangeably. In this post we’ll do our best to refer to them separately to avoid confusion.
Most Yogo sapphires are not heat treated
Because of how exceptionally clear Yogo sapphires are, their color looks far better than most natural sapphires on the market. This also means they are not heat treated to improve color and clarity. When Intergem Limited – the main Yogo sapphire mining company – made this claim in the later ’80s, it drew attention to the widespread practice of heating sapphires for better color and clarity. The result is the current legal requirement for all sapphire certificates to state whether they’ve been treated or not.
Most sapphires on the market are still heat treated, because rough sapphires are usually quite cloudy and their color isn’t as bright and vivid as you’d expect. So, even today, most sapphires are heat treated for color and clarity, but the practice is well known and expected.
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Quick history of Montana sapphire mining
Montana sapphire mining began in the late 1800s and very few sites were profitable. That is until the Yogo Gulch, initially part of a gold rush, was noted for both ‘blue pebbles’ and gold nuggets along the Yogo Creek. A few years later (1895) those pebbles were shipped to be assessed, when it was confirmed they were indeed sapphires, and very fine ones at that.
Several sapphire mines were established and sold until only one remained profitable, owned by American Yogo Sapphire Limited (later changed to Intergem Limited).
After Intergem Limited went out business, Yogo sapphires could be found with previous workers (paid in sapphires) and Citibank (the company’s creditors). The vast majority of Yogo sapphires in circulation today are these sapphires, and current mining in the Yogo area is very small-scale, mostly done by sapphire enthusiasts.
How are Montana sapphires different ?
Part of a sapphire’s worth is established by its origin. Not all sapphrie veins are the same, and two of the most precious are the Burma (Myanmar) and Ceylon (Sri Lanka) sapphires, hailed for their exceptional color. Montana sapphires are known not for their bright colors but for their very high clarity in rough form, something that is not common at all for sapphires. In fact most sapphires come out of the earth cloudy and not very impressive in color. It’s only after heating that they become as impressive as you see their final form.
Montana sapphires were hailed as the clearest and finest sapphires, mostly due to the prevalence of Yogo sapphires within Montana. Most Montana sapphires (Yogo or not) are very clean still, regardless of color.
Many Montana sapphires aren’t heat treated
The vast majority of sapphires sold all over the world are heat-treated, to intensify their color and to resolve most clarity issues. Heat treatments won’t resolve cracks and fractures, but they will resolve cloudiness by dissolving the fine rutile silk within the sapphire.
As most Montana sapphires are very clear, basically eye-clean, they don’t require a heat treatment for clarity. This also meant that the color you see on your Montana sapphire is the one the original rough had. If there was a heat treatment applied, it would be stated on the sapphire certificate under the ‘Treatment’ category.
Please note that some Montana sapphires are still heat treated ! It’s just a smaller percentage than sapphires of other origin.
Montana sapphires tend to be under 2 carats
The roughs mined in Montana tend to be smaller then the ones mined in other parts of the world. This results in most cut and polished sapphires being at 1-2 carats, which is a very common size for colored gemstones. But, this also means that any Montana sapphire over 2 carats will cost significantly more, as they’re a rarity just like a diamond over 1 carat.
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How much does a 1 carat Montana sapphire cost ?
A greenish-blue, eye-clean Montana sapphire will usually sell for $1,300 per carat (both treated and untreated). The lighter blue and light yellowish-green ones sell for a little less, around $1,100 per carat.
Meanwhile a blue sapphire not from Montana sells for about $3,000 per carat. Ceylon (Sri Lanka) and Burmese (Myanmar) blue sapphires fetch the highest prices, and of course the more vivid the cornflower blue, the higher the price. Again, most sapphires on the market will be heat treated, regardless of their origin. Untreated sapphires tend to cost more, but have a fainter color.
If you’re wondering why Montana sapphires aren’t worth more, it’s because in the end sapphire are judged by their color intensity, not by their clarity. And the fact of the matter is, Montana sapphires don’t have the most intense color, and when they do have a strong color it’s rarely the cornflower blue you’d expect from a sapphire.
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