Precious vs Semi-Precious Gemstones – What is the Difference?

If you have ever looked at buying a coloured gemstone, you will have probably come across the terms ‘precious’ and ‘semi-precious’ when it comes to gemstones and you might not be sure what these terms mean.

And it can be very confusing as you can have a $100/ct Diamond or Sapphire that are ‘precious stones’ and a $10,000/ct Black Opal or Colour-change Alexandrite that are ‘semi-precious’.

That is why I created this post to 1) hopefully clear this up and 2) hope that we stop using these stupid terms for gemstones!

What is the Difference Between a Precious and Semi-Precious Stone?

There isn’t one as there are no industry-recognised definitions as to what a precious or semi-precious gemstone is as there is no clear and definitive way to say which category a gem would fall into.

But there is a commonly referred to notion of precious and semi-precious gems on many blogs and even within the industry, where based on their perceived value, Diamonds, Emeralds, Sapphires and Rubies were called “precious stones” and all other gemstones were called “semi-precious stones”.

The problem with this very simple ideology is that it is completely flawed and as the gem trade and Gemmology (the study of gemstones) has continued to evolve, the notion of ‘precious’ and ‘semi-precious’ gemstones has become an antiquated one.

And even the definition of ‘semi-precious’ from two leading dictionaries doesn’t really help:

“A semiprecious stone is one that is used for making jewellery but is not extremely valuable” – Cambridge Dictionary

“of less commercial value than a precious stone” – Merriam-Webster Dictionary

Bit vague aren’t they?

When trying to make an argument for ‘precious’ and ‘semi-precious’ gemstones, many people talk about value and rarity, so let’s take a look at these two factors in more detail…

Gemstone Value

This is the most commonly used argument and is even referenced in the two dictionaries above but this is a flawed argument.

Let’s look at the price per carat of so-called ‘precious’ gems:

• Diamond – from less than $100 per carat to over $1 million per carat
• Emerald – from less than $30 per carat to over $100,000 per carat
• Sapphire – from less than $20 per carat to over $100,000 per carat
• Ruby – from less than $40 per carat to over $1 million per carat

As you can see, there is quite a large difference in the price per carat but there are many gemstones that can easily have a 4, 5 or even 6-figure price per carat and these include:

Now, I don’t know about you but calling a stone with a $1,000 per carat plus price tag ‘semi-precious’ doesn’t sound quite right to me!

And the argument becomes even less credible when calling a $100/carat Emerald or Ruby a ‘precious’ gem and a $2000/ct Paraiba Tourmaline or Colour-change Alexandrite a ‘semi-precious’ gem.

There are also many gemstones such as Aquamarine, Tanzanite and Jade that can easily fetch hundreds and potentially a thousand dollars per carat but I’m not sure at what point a gem becomes “extremely valuable”?

What About Low-Value Gems?

But what about the lower value gemstones such as Amethyst, Blue Topaz and Peridot, should we call these ‘semi-precious’ gems?

No, because we still don’t have a definition for what a ‘semi-precious’ gemstone is and as Walter Schuman quite rightly says in his Gemstones of the Word book (a must buy for anyone interested in gemstones), ‘semi-precious’ is quite a derogatory term.

This is because placing the term ‘semi-precious’ on any gemstone instantly devalues it in the eyes of many people and this isn’t something you want to do with any stone.

Yes, there are many gemstones out there that don’t have a lot of commercial value, mainly because that material is quite abundant but these stones can still have a lot of personal and sentimental value to the people who own them.

Valuing Gemstones

As the terms ‘precious’ and ‘semi-precious’ were formed based on the perceived value of the stones, let’s look at some of the factors we use to value gemstones.

When it comes to valuing a gem, there are many factors that impact the value of individual stones, such as:

• Colour
• Clarity
• Phenomenon – optical effects such as colour change, chatoyancy or asterism
• Nature – natural or synthetic
• Origin – where the stone was mined
• Treatments

And this is why two gems of the same variety can vary so much in terms of price.

Rarity

The second argument that people make is based on the rarity of the stone but once again, this is a flawed argument.

When it comes to rarity, comparing a stone to Diamond seems to be the standard as you will often see something like “xyz stone is rarer than diamond” and there are quite a few gemstones that are rarer than Diamond, such as:

• Colour-change Alexandrite
• Demantoid Garnet
• Tanzanite
• Black Opal
• Paraiba Tourmaline
• Natural Pearls

There are also some extremely rare gems such as Bixbite (Red Beryl) and Benitoite.

Just touching on Diamonds for a second, as a gem material they aren’t that rare but there are rare Diamonds, such as:

• Large colourless Diamonds that are free from inclusions
• Fancy colour Diamonds such as blue, pink, red, orange or purple

On the flip side of this are gemstones that are much more abundant, such as:

• Quartz varieties, including Amethyst and Smokey Quartz
• Feldspar varieties, including Labradorite and Moonstone
• Almandine & Pyrope Garnets
• Peridot

So if rarity is to be used to categorise gems as ‘precious’ or ‘semi-precious’, where do you draw the line? As with value, it simply isn’t possible due to not having enough reliable information about how many carats of each gem are mined every year.

Conclusion

I hope that this post has helped in your quest for knowledge about ‘precious’ and ‘semi-precious’ gemstones by explaining why the terms don’t work and breaking down the flaws in the “commonly accepted definitions” as there is a lot of bad information online around this subject (as there is for everything!).

As I final note for this post, I once asked my knowledgeable and highly respected Gemmology tutor what the difference was between a ‘precious’ and ‘semi-precious’ stone and his response:

“There isn’t one, all gemstones are precious”

And I couldn’t say it better myself.

Paul Haywood FGA DGA

I'm Paul Haywood FGA DGA, the owner and founder of Haywoods Gems, I'm a fully qualified Gemmologist and Diamond Grader from the Gemmological Association of Great Britain.

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