If you consider yourself a jewelry lover, you’re probably familiar with the terms “precious” and “semi-precious”. You might even know the four recognized precious gemstones. But do you know what it really means for a gem to be precious or semi-precious? The answer might not be as clean-cut as you’d hope! 

Precious Gemstones: The Big Four

For nearly two centuries, people have recognized Diamond, Emerald, Ruby, and Sapphire to be precious gemstones. At Amáli, you can usually find three of the “Big Four”. We carry Diamond, Emerald, and Ruby jewelry. These gemstones give an air of royalty and prestige. Occasionally, you’ll hear people refer to Emerald, Ruby, and Sapphire as the “Precious 3”, leaving Diamond out of the equation. This is because some people only include colored gemstones in their grouping. But keep in mind, Diamond has different color variations, and it is officially recognized as a precious gemstone. 

This pair of long 18k yellow gold and diamond earrings features five multicolored diamonds in chain wrapped bezels. The earrings fasten with a French hook closure.

So what makes these four gemstones precious? Surprisingly, the criteria for a precious gem is pretty arbitrary. But there’s history behind it, and history is always worth studying! In the mid-nineteenth century, jewelers decided to categorize gemstones into precious and semi-precious as a way to distinguish the perceived value of a select few gemstones. 

This distinguished category aka “precious gemstones” included the most popular, beautiful, and rare gemstones of the time. These gemstones were adored by royalty, included in cultural lore, and were rare enough to warrant a high selling price. Although it is not a strict requirement, all four of the precious gemstones are relatively scratch-resistant, making them ideal for jewelry. 

Ruby and Sapphire

While all four precious gemstones have similarities, no pair has more in common than Sapphire and Ruby. That’s because Sapphire and Ruby are both in the Corundum family. The same mineral is turned red by trace amounts of Chromium or blue by Iron and Titanium. Sapphires can actually come in other colors as well, like green or purple. The only color Sapphire can’t be is red, because a red Corundum is a Ruby. 

Like sisters, Sapphire and Ruby have some different behaviors. Notably, the crystal structure of Ruby tends to follow a different pattern than that of Sapphire. This isn’t always obvious to the naked eye, but it does contribute to Ruby’s shallow cut. Since Rubies are cut so shallowly, the end result can look like a mirror or a window into the stone itself. 

A model wears this oval Ruby pendant on an 18K yellow gold chain. Handmade gold bezel features braided detail and granulated prongs.

Is the Term “Precious Gem” Still Relevant? 

These days, there’s a lot of controversy around the precious gem nomenclature. The definition is too arbitrary to apply in a consistent fashion, and it’s not practical to keep the list constantly updated.  

One of the “requirements” for precious gemstones is to be rare. However, new deposits get discovered, which can quickly change how rare a gem is. For example, Amethyst was once considered a precious gem. But once huge deposits of Amethyst were discovered in Brazil, it lost its distinction as a precious gem. It’s a bit of a “Pluto” in the gem world. But this is one of the only updates we’ve seen to this centuries-old list, and of course Amethyst isn’t the only gem that’s become less rare over time. 

Are Precious Gemstones More Valuable? 

By definition precious gemstones hold a high value. However, precious gemstones aren’t necessarily more valuable than other gemstones. 

Gemstones come in all different shapes and sizes, and even within types of gemstones, there are so many variations. For example, Emeralds are incredibly expensive unless they are full of inclusions, which they often are. White Opal can be quite affordable, but Black Opal demands a jaw-dropping price tag. So is it possible to have an extremely high quality gemstone that is more expensive than a lower-quality precious gem? Absolutely! 

Value (and therefore price) comes from more than just a designation on “the list”. We like to keep our clients informed, so they know how to choose high-quality gemstones. In fact, nearly all of the gemstones we sell at Amáli have an accompanying blog for you to learn more about them! 

What is the Most Precious Gemstone? 

There isn’t a clear cut answer to which stone is the most precious. But the most valuable gemstone in the world is Blue Diamond, which sells for nearly $4million per carat. Not only is this precious gemstone rare, but it is also highly sought-after and highly scratch-resistant. 

There are other gemstones that are extremely rare though, including Tanzanite, Jadeite, and Black Opal. Interestingly, those three rare gemstones aren’t considered precious at all. So again, don’t confuse precious for valuable. 

The Forgotten Three–Pearl, Oriental Catseye, and Alexandrite

The “Big Four” get so much attention that you may not be familiar with the other three precious gemstones. That’s right…there’s technically seven! 

Oriental Catseye and Alexandrite are two of the rarest stones in the world, and they both have very unique qualities. Alexandrite changes color from day to night. It’s like the original mood ring! Oriental Catseye appears to have waves within, as well as a long ribbon of light cutting right down the middle. Both of these gemstones are so rare that it’s hard for them to gain as much popularity as Emerald or Diamond. 

Pearls have a remarkable life story, but their composition may be what holds them back from “the list”. Pearls are made within a mollusk, as part of the mollusk’s defense mechanism. No other gemstone is made from a living organism like this. So while many people consider Pearl to be a precious gem, some would argue that it’s not a gem at all. 


Textile Trio Earrings in Tahitian Pearl

Semi-Precious Gemstones 

Jewelers have kept it pretty simple for us. If it’s a gemstone and it’s not precious, it’s semiprecious. Everything “else” from Aquamarine to Tanzanite is considered semi-precious. Remember, these gemstones can be highly valuable too. There are Garnets that can sell for far more than most Emeralds. So don’t let the terminology hold you back. 

How to Choose Your Next Prized Piece

If there’s one thing to take away from this article, it’s to not get caught up in the labels! Sure the precious gemstones are stunning; that’s why they’ve been revered for centuries. But there are over 300 gemstones in the world, so why to limit yourself to just four?  


At the end of the day, your jewelry collection should be a reflection of YOU. So have fun exploring and learning about all the gemstones here on our blog!