Coloured Gemstone Engagement Rings: Emerald, Ruby, and Sapphire
A coloured gemstone engagement ring, set with an emerald, ruby, or sapphire, is a strong choice for anyone who wants something other than a diamond, but the three stones are not equally suited to daily wear. At Vanhess Jewellery in Coquitlam, BC, the first thing we talk through with a customer eyeing a coloured stone is hardness, because an engagement ring takes more knocks than any other piece of jewellery a person owns. Sapphire and ruby shrug those knocks off. Emerald needs more care. We have written about sapphire on its own before, so here we will dig into ruby and emerald in particular.
Hardness decides everything for an everyday ring
The Mohs scale ranks minerals by scratch resistance from 1 to 10. Diamond sits at 10. Ruby and sapphire, which are both the mineral corundum, sit at 9, making them the hardest gemstones after diamond, according to the GIA. Emerald, a variety of beryl, sits lower at 7.5 to 8, and it carries a second problem: it is usually full of internal inclusions that make it brittle and prone to chipping.
One thing to understand about the Mohs scale: it is not linear. As the International Gem Society notes, the jump from 9 to 10 is enormous. A diamond is many times harder than a corundum, even though they are only one number apart. The difference between a 7.5 emerald and a 9 sapphire is bigger than the single point suggests.
| Stone | Mineral | Mohs hardness | Daily-wear durability |
|---|---|---|---|
| Diamond | Carbon | 10 | Excellent |
| Ruby | Corundum | 9 | Excellent |
| Sapphire | Corundum | 9 | Excellent |
| Emerald | Beryl | 7.5-8 | Fair; brittle, chips, needs care |
Ruby: the toughest coloured choice
Ruby is red corundum, the same mineral as sapphire, just coloured by chromium instead of iron and titanium. At a Mohs 9 it is virtually scratch-proof in normal life, which makes it one of the best coloured stones for a ring you will never take off. It handles handwashing, gardening, and the daily bumps against door frames and keyboards that quietly wear down softer stones.
Red has obvious romantic appeal, and a good ruby holds its colour and life for generations. The main thing to know is that most rubies on the market are heat-treated to improve colour, which is a standard and stable treatment. Ask for disclosure, which any reputable seller provides. We do.
Emerald: beautiful, but handle with care
Emerald is the romantic's gamble. The green is unlike anything else, and a fine emerald is breathtaking in the literal sense. But at 7.5 to 8 on Mohs, and riddled with the natural inclusions the trade politely calls "jardin" (French for garden), emerald is brittle. A sharp knock on the right spot can chip or crack it. The vast majority of emeralds are also treated with oils or resins to fill surface-reaching fractures, and that treatment can degrade over time and with harsh cleaning.
None of that means you cannot have an emerald engagement ring. It means you have to wear it like the delicate thing it is. Take it off for sports, cleaning, and rough work. Never put it in an ultrasonic cleaner, which can blow out the fracture-filling. Clean it gently with mild soap and a soft cloth. A protective setting, like a bezel that wraps metal around the stone's edge, goes a long way. We steer emerald buyers toward bezels and halos for exactly this reason.
Meaning and why people choose colour
Coloured stones carry associations people enjoy: ruby with passion and energy, emerald with renewal and spring, sapphire with loyalty and calm. Birthstone connections matter to some buyers too. Plenty of people simply want a ring that is theirs and not the default. A blue, green, or red centre stone does that instantly.
There is also history here. Before diamonds dominated, coloured stones were the common choice for engagement rings, and they never fully went away. A coloured ring is not a gimmick, it is the older tradition.
A quick word on sapphire
We have a separate post on sapphire, but it deserves a mention here because it is the coloured stone we recommend most often. Sapphire is corundum, same as ruby, so it shares that Mohs 9 hardness and handles daily wear with no special fuss. It also comes in far more than blue: pink, yellow, green, peach, and the soft grey-blue tones that have been popular lately. If a customer wants a coloured engagement stone but is nervous about durability, sapphire is the easy answer. It gives you colour without the care routine an emerald demands.
Princess Diana's blue sapphire ring, now worn by Catherine, Princess of Wales, did a lot to keep sapphire in the public eye, and we still get customers who walk in asking for "the Diana ring." It is a fair request: a deep blue sapphire surrounded by diamonds is a hard look to beat, and the stone is tough enough to pass down.
Cost versus diamond
Coloured stones can cost less than a diamond of similar size, but fine ruby and top emerald in larger sizes get expensive fast, sometimes rivalling diamond per carat. Mid-quality sapphire and ruby tend to offer the most colour and durability for the money. Emerald pricing swings widely on clarity, since cleaner emeralds are rare. Set a budget and we will tell you honestly what it buys in each stone. Have a look at our engagement rings and our broader ring collection to get a feel for settings that suit coloured centres.
Key Takeaways
- For daily wear, ruby and sapphire (Mohs 9, both corundum) are excellent. Emerald (Mohs 7.5-8) is brittle and needs care.
- The Mohs scale is not linear, so the gap between emerald and sapphire is wider than one number suggests.
- Most rubies are heat-treated and most emeralds are oiled or resin-filled; ask for treatment disclosure.
- Protect an emerald with a bezel setting, gentle cleaning only, and no ultrasonic cleaner.
- Coloured stones can cost less than diamond, but fine ruby and emerald in larger sizes get pricey.
Frequently Asked Questions
Are sapphire, ruby, and emerald durable enough for an engagement ring?
Ruby and sapphire are. Both are corundum at Mohs 9, the hardest gems after diamond, and handle daily wear well. Emerald is riskier at Mohs 7.5-8 and is brittle with internal inclusions, so it needs a protective setting and gentle care.
Why is emerald more fragile than ruby or sapphire?
Emerald is softer at Mohs 7.5-8 and almost always contains natural inclusions and fractures that make it brittle. Those fractures are often filled with oil or resin, which can be damaged by knocks or harsh cleaning. Ruby and sapphire are harder and far tougher.
Is a coloured gemstone ring cheaper than a diamond?
Often, but not always. Mid-quality sapphire and ruby usually cost less than a diamond of similar size. Fine ruby and top-clarity emerald in larger sizes can match or exceed diamond prices per carat, because high-quality coloured stones are rare.
How should I care for an emerald engagement ring?
Take it off for sports, cleaning, and rough work. Clean it only with mild soap and a soft cloth, never an ultrasonic or steam cleaner, which can damage the fracture-filling. A bezel setting protects the stone's edges from chips.
Sources
- GIA - Sapphire (corundum, Mohs 9)
- International Gem Society - Gems Ordered by Mohs Hardness
- Wikipedia - Emerald (hardness, inclusions, treatments)
Data sourced June 2026. If you spot something out of date, let us know and we will update the guide as the trade evolves.
Visit Vanhess
We design coloured-stone engagement rings at our Coquitlam studio, 2929 Barnet Highway, Unit 2424, with an on-site goldsmith who can build a protective setting for a softer stone like emerald. Come see ruby, sapphire, and emerald under real light and feel the difference. Browse our engagement ring collection or call +1 (604) 653-6449 to book a time.
