Diamonds may be some girls' best friend, but they're not for everyone.

Yes they're beautiful, durable, sparkly and timeless, but they're also rather expensive and perhaps a little too classic, if you're the kind of lady who wants to wear something different on your ring finger.

Many grooms do feel they have to splash out on the traditional sparkler when it comes to popping the question, but the modern custom for diamond rings that cost three months' salary was actually only introduced as a marketing campaign by acclaimed jeweller, De Beers back in the 1930s. And it stuck!

But you don't have to follow suit.

Whether it's a clear stone that looks almost as sparkly as the real thing (no one has to know!), or a coloured stone that will set your ring apart, we've come up with 20 gorgeous alternative gems that will look just as precious as a diamond, when you say "Yes!".

1. Amethyst

Ring by Liz Phillips via Catbird

This pretty purple stone does tend to be seen in a raw state, but if it's well cut, it can look truly beautiful in fine jewellery.

At 7 on the Mohs scale (diamonds are 10), Amethysts may not be quite as hard, but they're still very durable and a fraction of the price! Pair the lavender hue with silver or rose gold for a gorgeous, romantic setting or set with other colours for something a little quirkier.

2. Turquoise

Ring by Mociun

Turquoise has become a really trendy stone over the last few years with leading alternative jewellery brands like Azlee and Mociun using it across their collections.

Turquoise ranges from 5 to 7 on the Mohs scale and with a composition of copper and aluminium, it can range from a pure bright blue, to a pale hue with flecks of metal. Pair with small diamonds in the setting for a luxe finish to a matte stone.

3. Sapphire

Ring by Kristin Coffin on Etsy

Sapphires are typically a blue precious stone, but they do also come in other hues like peach, pink, yellow, green and white.

At 9 on the Mohs scale, sapphires are the third hardest mineral, and at about a third of the price, they make the perfect diamond substitute. While a white sapphire won't capture quite the same sparkle as a diamond, if it's well cut, it can look almost as good, giving more bling for your buck if you're looking for a larger stone.

4. Emerald

Ring by Ferguson's Fine Jewellery on Etsy

Emerald, with their distinct rich green tone, are beautiful, luxe, and precious, which makes them a popular stone for engagement rings.

While they have fallen out of style over recent years, added to a modern setting, they can look both chic and timeless, and at 7.5 to 8 on the Mohs scale, emeralds can be forever too!

5. Morganite

Ring by Astley Clarke

Romantic, feminine and oh-so-pretty, morganite (set in a diamond halo) is perhaps one of the most popular choices for engagement rings at the moment.

As a beryl, morganite is from the same family of stones as emeralds, siting 7.5 to 8 on the Mohs scale. The price of morganites can vary wildly, so do your research and talk to your jeweller about the cut and quality of your stone.

6. Garnet

Ring by Maejean Vintage on Etsy

Garnets come in all manner of colours but are most typically this rich pinky-red hue. Often found in antique settings, these stones look really pretty paired with pearls or stones of other colours.

At 6.5 to 7.5, they're not quite as hard as their ruby counterparts, but this is reflected in the price. A gorgeous choice for a less expensive engagement ring.

7. Pearl

Ring by Melanie Georgacopoulos via Matches

Pearls are beautiful and iconic, whether they are in a luxe antique setting or a chic modern ring. The bad news is though, that pearls are made from calcium carbonate, which means at 2.5 to 4.5 on the Mohs scale, they will scratch and tarnish easily.

Select a pearl engagement ring if you plan to wear it only occasionally, or if you choose smaller pearls, set into surround of hardier gemstones.

8. Moissanite

Rings by Rare Earth on Etsy

If you're looking for the glamour and hardiness of a diamond, without the epic price tag, a moissanite might be the stone for you.

When they were first discovered 120 years ago, these beautiful clear (or sometimes green or yellow) stones were mistaken for diamonds. At 9.5 on the Mohs scale, they are just behind diamonds as the second hardest mineral in the world, making them a more than adequate substitute when well-cut. Pair with a diamond halo for added sparkle.

9. Lapis Lazuli

Ring by Collyer's Mansion

These deep matte blue semi-precious stones are often overlooked for engagement rings but with the most captivating colours and beautiful gold flecks they can add a really opulent touch to a gold setting. It hasn't been used in many engagement rings before now, but we reckon it's following turquoise's steps and is set to be popular in the coming years.

Relatively inexpensive, lapis can range from $1 to $150 dollars per carat, but the very finest stones are an even, intense blue with a light dusting of gold and no cracks. The lapis pigment is renowned for its lasting quality but at 5 to 5.5 on the Mohs scale your stone may scratch and perhaps need replacing every few years.

10. Tourmaline

Ring by Polly Wales via Catbird

Tourmaline is a mineral that comes often forms as a mix of two or three colours, but for fine jewellery, its green variety has become increasingly popular.

At 7 to 7.5 on the Mohs scale, tourmaline is still quite hardy, and with a cloudier look than an emerald, scratches won't be quite so obvious. Tourmaline looks beautiful in a bohemian or baroque style setting, especially mixed with different colour gem stones.

11. Topaz

Ring by Ippolita via Bergdorf Goodman

Topaz, with its dazzling array of colours and luxe clarity, is a natural choice for engagement rings. While they can differ in their mineral content, topaz gemstones tend to be an 8 on the Mohs scale.

A pure topaz is actually colourless, and the blue, orange, red, green and pink hues are actually created by imperfections in the stone. We think that beautiful quirk makes them a sweet stone to give your other half on your engagement!

12. Opal

Ring by Erica Weiner

Opals make the most beautifully unique clusters, and while they were seen as old-fashioned, over the last few years, they've been making a comeback. Opals come in black, white and crystal and depending on their vibrancy, they reflect the entire rainbow as they move and dazzle - because of this, no two opals are ever the same.

Avoid choosing a dull stone and look for gems with pretty patterns and antique settings. At 5.5 to 6.5 on the Mohs scale, opals are not as hardy as other gems, but do make beautiful engagement ring stones if you don't mind a little tarnish or if you plan to wear your ring only occasionally.

13. Ruby

Ring by Crystal Casman Jewellery on Etsy

Like emeralds and sapphires, rubies are one of the four precious stones, making them an extremely popular choice for engagement rings with their rich, luxurious blood-red tone.

At 9 on the Mohs scale, rubies will survive on even the busiest hands, this is reflected in the price though, with the finest rubies often fetching more that their diamond counterparts. If you're shopping for a ruby, look for the same four Cs as diamonds (with a rich colour being the most important) but also ask about the origin - Burmese rubies tend to be the most expensive.

14. Onyx

Ring by Mociun

Onyx is a beautiful mineral that comes in a variety of colours but it most commonly found in its black form for fine jewellery.

A dense, yet silky stone, (at 6 to 7 on the Mohs scale) Onyx would make a unique and utterly stylish addition to your engagement ring - plus as a black stone, will be timeless and chic. Pair with black diamonds, or even clear ones for a really opulent look.

15. Peridot

Ring by Studio 1980 on Etsy

Peridots are one of the few gemstones in the world that only appear in one colour, a beautiful, olive-green. While sometimes mistaken for emeralds, peridots tend to be brighter in colour, thought not as hard at 6.5 to 7 on the Mohs scale.

Peridots are often considered a token of love (Napoleon famously gifted his first wife Josephine with one with that symbolism of his admiration) making them a rather romantic engagement ring gemstone.

16. Labradorite

Ring by Irene Neuwirth via Barneys

Labradorite has become increasingly stylish in fine cocktail rings and earrings over the last few years, so it was only a matter of time before it made it into engagement rings as well. This mineral can range from black to brown to blue, (though its grey-brown hue is most common in luxury jewellery) and ranges from 6 to 6.5 on the Mohs scale.

The mineral is regarded for its strengthening and shielding properties and legend has it that Inuits saw Labradorite falling from Aurora Borealis in the sky, making this a rather magical and special stone for your engagement ring.

17. Aquamarine

Ring by Alex Monroe

Aquamarine is a beautiful pale blue semi precious gemstone that's found its footing as a stylish choice for engagement rings. The beryl stone is quite hardy at 7.5 to 8 on the Mohs scale, and as a cousin of the emerald, it can appear particularly dazzling when well-cut.

Aquamarines have beautiful clarity, making them look expensive, they are also known as a "lucky stone", the perfect charm as you enter married life.

18. Sunstone

Ring by Mociun

Sunstones are an under-the-radar gemstone, often overshadowed by the more popular moonstones, but stylish designers like Mociun are pairing them with more precious stones to make beautiful cluster combinations.

These peachy (but often red, pink, orange or even green) coloured crystals are most commonly found in Norway and the US (they're the official gemstone of Oregon!) and are 6 to 7 on the Mohs scale. Closely linked to Labradorite, sunstones are seen as an abundance mineral, bringing prosperity, vitality and fearlessness to the wearer.

19. Tsavorite

Ring by Crystal Casman Jewelry on Etsy

Tsavorite is a beautiful bright green stone from the garnet family that makes a striking addition to any piece of jewellery. At 7 to 7.5 on the Mohs scale, it's a hardy stone, that can look really dazzling when well cut, and set among gold and diamonds.

Like its counterpart Tanzanite (below) this stone was discovered in Tanzania in the sixties and had its profile raised by Tiffany & Co. While not quite as rare or expensive as Tanzanite, if you're looking for a green stone for your engagement ring, Tsavorite is a beautiful alternative.

20. Tanzanite

Ring by Tiffany & Co

Tanzanite is a rare and beautiful gemstone that was only discovered in the sixties. It ranges from 6.5 to 7 on the Mohs scale. Tanzanite's name was actually given to it by Tiffany & Co (who are big fans of this blueish purplish stone) after its place of origin, in Northern Tanzania.

1000 times rarer than diamonds, Tanzanite is a fitting stone to give your one in a million, and with only an estimated 30-year supply left in the world, this is a particularly precious choice for an engagement ring.

So, there you have it, our favourite alternative gemstones for your all important engagement ring!

Did you shun the traditional diamond? We'd love to hear about your unique engagement rings in the comments below.

Planning to pop the question soon? Check out these awesome proposal stories for inspiration!