Since ancient times, gemstones have been desirable collector’s items for the rich and famous, and are just as popular today. From human adornments to intricate jewellery and even currency, gemstones have many uses. There are also many different varieties, shapes, sizes, and cuts, each offering vibrant colours and dazzling beauty.

In our guide, we cover what exactly are gemstones, how they are formed, and what the most popular types are.

What are gemstones?

Before we delve further, it’s important to define what gemstones actually are. Essentially, gemstones are naturally occurring rocks or minerals that are cut, polished, and manufactured into incredible pieces of jewellery or other decorative items.

They are formed in the Earth’s crust, where they crystallise under immense heat and pressure. This isn’t something that occurs overnight either, and can take up to thousands or even millions of years before the gemstones we know and love today are produced.

The chemical composition of each type of gemstone differs, each with its own unique structure, which is why we see so many different variations. The rarity of some of these is what makes them so valuable.

Gemstones are distinguished into two categories, precious and semi-precious, with the distinction being their hardness – or scratch resistance. However, this classification isn’t as important now and the value of the gemstone is determined by its quality.

Types of gemstones

While we could cover every gemstone in existence, the list would never end. That’s why we’ve included some of our favourites and what makes them so special.


Diamonds truly are a girl’s best friend and, as the hardest mineral substance, they are built to last a lifetime. In pure form, diamonds are colourless but, as with all gems, they can also range from near colourless to coloured.

They are among the most treasured precious stones in the world and are often featured in engagement rings and eternity rings due to their brilliance and elegance. The white diamond is the most common of all but recent trends have included pink, green, and orange variations.


Only second to the diamond, sapphire is another precious gemstone most known for its deep blue shade. They’re part of the corundum family, with all colours being considered sapphire except for red.

Ancient cultures associated the stone with magic and good luck hence why it is often set alongside diamonds, for those looking to express their love and lifelong commitment. They’ve even been thought to protect against poisons as well as envy and harm, featuring in jewellery alongside gold and silver.


One of the newer gemstones used in jewellery, discovered as recently as 1967, tanzanite is a rare semi-precious stone with a deep purple or violet-blue sparkle. While not as hard as the ‘big four’ precious stones, its rarity means it is sometimes even more sought after.

As the name suggests, these beautiful gems are only found in Tanzania, adding to their limited availability. Tanzanite is almost exclusively paired with silver, either in the form of rings or pendants.


Though opal is thought of as a white gemstone, it actually produces an iridescent play of colours that can only be compared to that of a kaleidoscope. The colours are a result of tiny amounts of silica and moisture trapped inside the stone. It’s this uniqueness that has led to them being used in a number of different creations.

Some jewellers even argue that opal is the fifth precious stone. There are also more variations of opal, such as pink opal and black opal. The latter is generally the most valuable, especially those that are opaque, due to its rarity. Regardless of whether they are turned into earrings, rings, or necklaces, these gemstones truly are one of a kind.