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What makes a gemstone rare?

Updated: Jul 18, 2023

What makes something rare? Does this mean it’s valuable?

Rarity and value are often, but not always, linked. Desirability plays an important part in value to.

What makes something rare? Quite simply there isn’t much of it about. This can mean different things depending on what you are talking about. I’m going to use examples from one of my own collecting interests, gemstones (although there are many more areas I collect).

What is a gemstone? Well, there are many definitions out there for this, but my own personal answer is, any natural or man-made material, that can cut and polished to enhance its beauty. There are purists that certainly wouldn’t agree and say it should be a natural mineral or organic compound such as Quartz or Amber, to be set in jewellery, but I think it should be a little more open. Why? Because there are some pretty cool man-made materials out there that have been used to spectacular effect. As a for instance, Google Fordite, entirely man-made, but it can be stunning.

Now that bit is out of the way, onto rarity. What makes a gemstone rare? This does get into science a bit, but I will keep it as light as I can. How rare are the elements that make the raw material? What kind of conditions are needed for the material to form? How easy is it to extract the material? Is it easy to handle, cut and polish? Is it from a particular location? These are the first set of questions, many more come after this which are mostly to do with quality.

Both Oxygen (O) and Aluminium (Al) are very common, when they combine they can form corundum. If this particular Corundum absorbs a bit of Chromium (Cr), that’s much less plentiful, You’ll end up with a bright red Ruby. Now if that Ruby is forming near a bit of Iron (Fe), which is much more plentiful again, the bright red colour will become a bit more brown. So it’s rarer to get the right combination to produce a stunning gem than an OK one.

Cerussite and Sulphur are both substances that are pretty common and can be bought by the kilo for not much money. But a cut gemstone on the other hand is an entirely different matter. Cerrusite is tricky to cut and polish as it has a tendency to crumble or cleave (split) when you are working with it. I heard of a tale once where a crystal of 450 grams was given to a skilled lapidary (gem cutter) and after all the cutting was done, 2 gems of less than 0.20 grams were presented as all that was left, and I can quite believe it! Sulphur is worse. It is so sensitive to heat, that if you hold a crystal in your hand, you can crack it and even burst it. Imagine trying to cut that without getting it the slightest bit warm! This makes these fairly, to very rare.

Other things such as maximum sizes due to how they are extracted. Tsavorite, a bright, intense, green Garnet is rarely extracted as large crystals. They do form, but have to be blasted out of their tough parent rock. So the large crystals often become little pieces in the blink of an eye. This makes much larger gemstones much rarer. Painite is another. Very much a collectors’ stone, but you never find large ones as you rarely find large crystals.

Certain man-made gemstones are rare also. There can be a number of reasons for this, such as the method of manufacture or colour. One example is man-made Quartz, manufactured by Seiko, yes the watch people. They used a method to fuse quartz together in an attempt to get a better quartz for watches. The method they used was pretty inefficient and took a lot of energy to make an inferior product to what was already being produced. A few of these examples were cut as curiosities and are out there somewhere, but are VERY rare, rarer than cut Sulphur in fact. Other man-made gems that are pretty rare are some of the predecessors of the Diamond simulant (look alike) Cubic Zirconia (CZ), especially some of the coloured examples like the pink YAG (Yttrium Aluminium Garnet) and peach coloured GGG (Gadolinium Gallium Garnet).

Gemstones that “do” things are rarer than the usual varieties. Gems that change colour, react to different lights and appear to glow, show patterns from reflections such as cats eyes and stars, to play of colour such as Opals, all add to the rarity. Some even do more than one thing, Google Cats Eye Alexandrite to see what I mean.

Opals come in many shapes, sizes and types, costing very little to eye wateringly expensive.

Opals are becoming rarer, especially larger size pieces. Each piece is unique as their colour pattern is unlike any other gem. Top quality Black Opals can cost more than an average family home.

You've already read about the rarity of all the ingredients for a gem being in one place, but what about those gems that contain more than one species?

Some of my collection of Gemstones with inclusions, mostly quartz.

Some inclusions, bits inside a gemstone, can be highly collectable as well. I have a particular interest in these. When minerals form, they often trap other things inside them, which is where inclusions such as the ones on the picture above. Some of these are relatively common, but some are very difficult to find and new ones are still being found. These inclusions can be in all sorts of Gems, such as Garnet Crystals in Diamonds and Etch channels in Diamonds (one I've yet to get a good example of). These etch channels look like a wobbly rectangular tube and from my pout of view, are very cool.

So, does rare equal valuable? Not always. This comes down to the old “supply and demand” situation. There are far more people who would wish to own a fine, bright red, Burmese Ruby than a milky, greyish white Cerussite or murky colourless Seiko Quartz. Beauty is an important factor that directly influences its desirability and therefore value. If it doesn’t look pretty, who will buy it (probably me)? At the top end of jewellery collectors, there are a select few that are hunting down what they don’t have yet, which could be one of the varieties you don’t know of yet. But if a colour changing, star, opal turns up, I’m sure there will be a line of buyers for it.

I hope that explains this a little. If you need any more information, please feel free to get in touch.

Best wishes,


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