Coloured Stone Rings: Beware Of Which You Pick

Coloured stones make for meaningful and gorgeous rings, whether for yourself, a gift or an engagement. But the durability of certain gems for everyday use is often overlooked, or not known at all, too unassuming buyers. Not all precious stones are equal when it comes to resilience.

Some, such as diamond, can withstand pressure and knocks without getting so much as a scratch – it is the hardest substance on earth, after all. Others, while looking exquisitely beautiful and being extraordinarily expensive, are surprisingly fragile and could crack or chip with an unsuspecting bump or careless fall. This is why some precious gems are reserved for fine jewellery, to be worn rarely and with great aplomb, and then stored carefully in jewellery boxes and cases, preserved until it’s next exhibit.  

But engagement rings are meant to be worn daily. And with coloured gemstones becoming more and more popular, many brides-to-be look at these more unique options over the traditional diamond. Brilliant blue sapphires for Virgos, azure aquamarine for Pisces or ravishing red ruby for those fall under the zodiac sign of Leo.

MOHS Hardness Scale: The Measure For Hardness in Gemstones

MOHS Hardness Scale

MOHS Hardness Scale is a measure for the hardness of minerals based on the ability of one mineral to scratch another. On this scale, invented and named after Friedrich Mohs, there are ten minerals, ranging from softest to hardest: talc, gypsum, calcite, fluorite, apatite, feldspar, quartz, topaz, corundum and diamond (scoring 10), which is the hardest and has the ability to scratch the lot. This scale is used by precious stone experts and jewellery buyers to gauge the durability of the gem they are purchasing. Generally, when considering buying a gemstone ring for everyday use, such as an engagement ring, a stone should score more than 7.5 or MOHS Hardness Scale to be a viable option against scratches and damage.   

What not to wear?

Opals (5.5-6.5), emeralds (7.5), tanzanite (6.5-7), turquoise (5-6), alexandrite and zircon are all beautiful choices for jewellery but, unfortunately, they’re not tough enough to stand daily wear. So if you are looking for a ring (these get knocked about quite a lot as they’re on your hand) or bracelet with these gems in it to wear often, it will be better to invest your money in a jewellery set with more robust stones. Pearl is another choice that you may want to save for a special necklace or set of earrings rather than a ring as it is easily damaged, with a score of just 2.5 on the MOHS Hardness Scale.

A Quick Guide To Birthstone Hardness

In case you were looking to purchase a birthstone by zodiac for a ring, here’s what you need to know about the hardness of each gem associated with a particular zodiac sign.

Zodiac Sign: Aries

  • Birthstone: Diamond
  • MOHS Hardness Scale: 10

Aries’ birthstone is the beautiful diamond, which is known as the hardest substance on earth. Buying a diamond ring is the most popular choice for engagements and gifting, and its durability incomparably superior to other stones  

Zodiac Sign: Taurus

  • Birthstone: Emerald
  • MOHS Hardness Scale: 7.5-8.

The Taurus birthstone emerald, in addition to being on the borderline of recommended hardness also has small cavities within them called inclusions that add to their fragility. Not a good pick for an everyday ring.

Zodiac Sign: Gemini

  • Birthstones: Pearl, Moonstone and Alexandrite
  • MOHS Hardness Scale: 2.5

Its low score makes Gemini’s birthstone of pearl an absolute wrong choice for an engagement ring. Gemini’s birthstone alternative, moonstone, scores 6-6.5, which also makes it a poor choice. However, there is a third alternative in Alexandrites, which is a hardy(ish) 8.5 on the MOHS Hardness Scale.

Zodiac Sign: Cancer

  • Birthstone: Ruby
  • MOHS Hardness Scale: 9

Cancer’s birthstone is ruby and, after diamond, this is an ideal choice for a ring as it can withstand everyday wear.

Zodiac Sign: Leo

  • Birthstone: Peridot
  • MOHS Hardness Scale: 7

With a score of 7, Leo’s birthstone Peridot is an avoidable choice for a ring. Those looking for a birthstone jewel can instead choose spinel, which has a score of 8 on the MOHS Hardness Scale.

Zodiac Sign: Virgo

  • Birthstone: Sapphire
  • MOHS Hardness Scale: 9.0

With a high ranking on the scale, Virgo’s birthstone sapphire is perfectly suited to an engagement ring for everyday wear.

Zodiac Sign: Libra

  • Birthstones: Opal
  • MOHS Hardness Scale: 5.5-6.5

Libra’s birthstone opal can be damaged easily and are amongst the least hardy birthstones so we’d suggest you leave them as pendants or earrings. Libra’s alternative birthstone tourmalines have a rating of 7-7.5, so it doesn’t quite make the cut either. You could try sapphire, which is a stone that is said to influence Libras positively.

Zodiac Sign: Scorpio


  • Birthstones: Topaz
  • MOHS Hardness Scale: 8

Zodiac birthstone Topaz makes a great option as an everyday ring or engagement ring for those born under the star sign of Scorpio.

Zodiac Sign: Sagittarius

Blue Zircon

  • Birthstones: Blue Zircon
  • MOHS Hardness Scale: 7.5

While not extremely low on the hardness scale, Sagittarius zodiac gem blue zircon is still not among the harder gems on the list so setting it into a ring should proceed only if you plan on being extremely cautious. A good alternative is a blue topaz, which is also a lucky stone for Sagittarius and has a score of 8 on MOHS hardness scale.

Zodiac Sign: Capricorn

  • Birthstone: Garnet
  • MOHS Hardness Scale: 6.5-7.5

Capricorn birthstone garnet is not recommended for everyday rings as its hardness is not high enough to withstand knocks that tend to occur with daily wear. Garnet is the primary zodiac birthstone for Capricorn. However, those born under this sign may also benefit from wearing sapphire, blue topaz, turquoise and ruby.

Zodiac Sign: Aquarius


  • Birthstone: Amethyst
  • MOHS Hardness Scale: 7.0

Much as Capricorn’s birthstone above, Aquarius birthstone amethyst is also not an ideal choice for an engagement ring that will be born on a daily basis.

Zodiac Sign: Pisces Aquamarine


  • Birthstone: Aquamarine
  • MOHS Hardness Scale: 7.5-8.0

Beautiful blue Pisces zodiac gemstone aquamarine is not extremely hard but it is not so weak that it cannot withstand some amount of pressure. It’s a good choice for an engagement ring; just be careful when you wear it and maybe keep it in its box when doing hands-on tasks.

While birthstone engagement rings are becoming more and more in trend as couples look for unique symbols to represent their union, it’s important to get the most from your purchase price. Precious gems don’t come cheap and spending a huge sum of money is justifiable on jewellery you are not likely to damage easily – pieces that will last a lifetime. So choose your rings wisely and leave the beautiful but more delicate stones for special-occasion jewellery.  


  1. Rose
    December 10, 2018 / 10:03 pm

    My hands are very small. What engagement ring style is best?