Ruby

Is ruby durable enough for an engagement ring?

Yes — ruby is one of the best coloured-stone choices for a ring you'll wear every day. It sits at 9 on the Mohs scale, which measures scratch resistance, putting it right behind diamond at 10 and ahead of almost everything else you'll meet in a jewellery case (GIA). On our bench in Coquitlam, ruby is one of the few non-diamond stones I'm comfortable recommending for a centre stone that has to survive dishes, gym sessions and a decade of hand-knocks.

Ruby is a variety of the mineral corundum. The red comes from traces of chromium; swap that for other trace elements and the same mineral becomes a sapphire. So ruby and sapphire are chemically twins — only the colour name changes. Both are far harder than emerald, which is brittle and prone to chipping, and that single fact is why ruby and sapphire dominate the short list of stones that hold up to engagement-ring life.

Hardness is not the whole story, though. A stone can be hard and still break along a sharp blow, and heavily included or treated rubies are more fragile than clean natural ones. The treatment a ruby has had matters as much as its Mohs number — more on that below.

How ruby colour is graded

With ruby, colour is king. Clarity and cut matter, but two rubies of identical size can differ in price many times over based on red alone. Graders break colour into three parts:

• Hue — the actual colour. The most valued rubies are pure red to slightly purplish-red. Too much orange or brown drops the value.
• Tone — how light or dark the stone is. The best rubies are medium to medium-dark; too pale reads as pink, too dark goes muddy.
• Saturation — how vivid the colour is. Strong, "vivid" saturation is what makes a ruby glow rather than look greyish.

The famous benchmark is "pigeon's blood" red — a vivid red with a faint blue undertone and strong saturation. In the trade, top labs reserve that grade for the finest material, and many of the highest definitions also require the stone to be unheated (Sotheby's). True pigeon's-blood rubies are rare and sell for enormous per-carat prices. Most rings use lovely reds a step or two below that ceiling, which is where the sensible money is.

Where ruby differs from a colourless lab-grown stone like moissanite is that its appeal is the colour itself, not brilliance or sparkle. You're buying red, so trust your eye in good daylight more than any single grading word.

Ruby treatments: heat vs lead-glass filling

Almost all rubies in the market have been treated, and the kind of treatment changes both value and durability. Disclosure is the whole game here — a reputable jeweller tells you exactly what's been done.

• Heat treatment is the standard, widely accepted enhancement. Controlled heating improves colour and clarity and is stable for normal wear (Jewelers of America). A heated ruby is still a real ruby; it just isn't priced like the rare unheated material.
• Lead-glass (composite) filling is different. Low-grade, heavily fractured ruby is fused with lead glass to fill the cracks — sometimes a large share of the finished stone is glass. These "composite rubies" look bright and cost little, but the glass needs far more care than untreated or heat-treated ruby: chemicals can damage it, and even a mild substance like lemon juice can attack the high-lead glass (GIA). They must be disclosed and shouldn't be sold simply as "ruby".

This is exactly why a local jeweller matters. When a customer brings in an inherited "ruby" for resizing, the first thing our on-site goldsmith checks is whether it's glass-filled — because torch heat and pickling solutions that are routine for a natural ruby can ruin a composite stone. If you're shopping, ask one plain question: has this been heated only, or is it lead-glass filled? The answer should be in writing.

Ruby treatment comparison

How to care for a ruby ring

A natural or heat-treated ruby is easy to live with. Warm water, mild dish soap and a soft brush clean it beautifully, and ultrasonic and steam cleaners are generally safe for untreated and heat-only stones (GIA). Take the ring off for heavy manual work and store it apart from softer gems so it doesn't scratch them — at Mohs 9 your ruby will happily scuff a softer stone in the same pouch.

If a stone is lead-glass filled, the rules flip: keep it away from heat, ultrasonic cleaners and any chemical, and tell any jeweller before repair so they don't apply a torch to it. When in doubt about an older or unmarked ruby, bring it in and we'll identify the treatment before anyone touches it.

For a fuller comparison of which coloured stones survive daily wear, see our main Gemstone Guide: Durability, Colour & Care, Stone by Stone, or read about other centre-stone options in Beyond Diamonds: Alternative Stones.

Frequently Asked Questions