The common diamond alternatives for an engagement ring are moissanite, white sapphire, ruby and colored sapphire, morganite, emerald, cubic zirconia and colorless zircon, and the number that separates them for daily wear is hardness, which GIA publishes stone by stone. None is a diamond, and in the US the FTC Jewelry Guides say the seller must say so on the label.
Below, each hardness figure carries the page it came from, plus the wording a label needs and what a Mohs number never tells you.
Key Takeaways
- GIA puts moissanite at 9.25 on the Mohs scale, second only to diamond.
- On GIA’s figures, colorless and colored sapphire and ruby sit at 9, cubic zirconia at 8 to 8.5, morganite and emerald at 7.5 to 8, colorless zircon at 6 to 7.5.
- GIA says cubic zirconia often costs less than 5% of a comparable diamond.
- FTC guidance (16 CFR 23.25(b)) says a simulated or laboratory-created stone must carry that word immediately before the stone’s name, and that “faux” is not adequate disclosure.
- Hardness is resistance to scratching, not breaking: GIA calls diamond extremely hard but only somewhat tough.
What Counts as a Diamond Alternative?
A diamond alternative is a different material chosen to sit where a diamond would, for the resemblance or for its own sake.
Simulants: Different Material, Similar Look
GIA groups the look-alikes as simulants: materials that flash and dazzle like a diamond but are not diamonds, commonly glass, moissanite or cubic zirconia, unrelated to diamond at the atomic level and identifiable by their optical and physical characteristics (GIA, Simulants, Moissanite and Lab-Grown Diamonds, accessed 11/09/2026). Sapphire, ruby, emerald and morganite are not simulants at all.
A Lab-Grown Diamond Is Not an Alternative
GIA says lab-grown diamonds have essentially the same chemical composition and crystal structure as diamonds created by nature, which makes them a different comparison: lab grown vs natural diamond.
What the Label Has to Say
When a gem name describes a created or simulated stone, FTC guidance says “laboratory-grown”, “laboratory-created”, “[manufacturer name]-created”, “imitation” or “simulated” must come immediately before it, with equal conspicuousness (16 CFR 23.25(b), 2018 text), and a Note under the same section says “faux” is not an adequate disclosure. The FTC defines a diamond as a mineral of essentially pure carbon crystallized in the isometric system, hardness 10 (16 CFR 23.12(a), 2018, accessed 11/09/2026), so nothing here can be sold as one.
Diamond Alternatives Compared, With the Source for Every Number
Most pages comparing these stones print Mohs numbers with no source. Every figure below names the page it was read on.
| Stone | What it is | Mohs hardness | Source |
|---|---|---|---|
| Diamond (the baseline) | A mineral of essentially pure carbon crystallized in the isometric system | 10 | FTC Jewelry Guides, 16 CFR 23.12(a) |
| Moissanite | Silicon carbide | 9.25 | GIA, Diamond Alternatives: Engagement Rings (accessed 2026) |
| Colorless (white) sapphire | Natural gem, corundum | 9 | GIA, Diamond Alternatives: Engagement Rings |
| Ruby and colored sapphire | Natural gem, corundum | 9 | GIA, Diamond Alternatives: Engagement Rings |
| Cubic zirconia | Melted powdered zirconium oxide, a simulant | 8 to 8.5 | GIA, Diamond Alternatives: Engagement Rings |
| Morganite | Natural gem, beryl | 7.5 to 8 | GIA, Diamond Alternatives: Engagement Rings |
| Emerald | Natural gem, beryl | 7.5 to 8 | GIA, Diamond Alternatives: Engagement Rings |
| Colorless zircon | A natural gem, and not the same thing as cubic zirconia | 6 to 7.5 | GIA, Jewelry Buyers Guide to Diamond Alternatives |
The Mohs scale measures resistance to scratching only, and each published value describes the pure material, not the finished ring.
Alternative Stones for an Engagement Ring, One by One
Here is what GIA publishes about each of the alternative stones for engagement ring centers, caveats included.
Moissanite
Moissanite is silicon carbide, and GIA gives it 9.25 on the Mohs scale, very hard and durable although not as hard as diamond (GIA, An Introduction to Imitation Diamonds & Other Gems, accessed 11/09/2026). On cost GIA says only that moissanite costs much less than comparable diamonds, letting buyers select larger stones or more intricate designs within their budget; it publishes no figure, and neither do we. The caveat is GIA’s own: some moissanites look slightly yellow or gray at certain angles.
White Sapphire, Ruby and Colored Sapphire
GIA puts colorless sapphire at 9 on the Mohs scale, one of the hardest gemstones available behind only diamond and moissanite, and calls it well suited for everyday wear (GIA, Diamond Alternatives: Engagement Rings, accessed 11/09/2026). Colored sapphire scores 9 on the same figures, and GIA says rubies are one of the hardest gemstones at 9, ideal for everyday wear. All three are corundum, natural gems in their own right rather than imitations of anything.
Morganite and Emerald
GIA ranks morganite and emerald at 7.5 to 8 on the Mohs scale, calling morganite fairly durable and suitable for everyday wear and saying plainly that emeralds are softer than diamonds. The consequence sits in the setting rather than the stone: a softer center stone worn every day is better off with its edges covered, which is what a bezel setting does.
Cubic Zirconia and Colorless Zircon (Two Different Things)
Cubic zirconia is made by placing powdered zirconium oxide inside a metal chamber and heating it to its melting point; colorless zircon is a separate natural gem. The names confuse buyers; the figures do not match. GIA gives cubic zirconia 8 to 8.5 on the Mohs scale, durable and suitable for everyday wear though less hard than diamond or moissanite and more prone to scratches and abrasions over time, and notes elsewhere that colorless CZ has been shown to yellow and can be somewhat brittle. Colorless zircon sits at 6 to 7.5 and, GIA says, requires more care and must never be cleaned with an ultrasonic or steam cleaner (GIA, Jewelry Buyers Guide to Diamond Alternatives, accessed 11/09/2026).
Hardness Is Not the Whole of Durability
A high Mohs number tells you a stone resists scratching. It says nothing about breaking.
Hard, but Not Necessarily Tough
GIA describes diamond as very stable and extremely hard, but only somewhat tough, with hardness uneven along different directions of the crystal, and defines toughness as how well a gemstone resists breaking and chipping (GIA, Al Gilbertson, How to Protect Your Diamond from Chipping, 2016). Chips typically occur when the girdle or point strikes something hard, the same paper says, with countertops and rings worn side by side among the common causes, and vulnerable points or corners do better in bezels, partial bezels or V-shaped prongs. GIA publishes that discussion for diamond alone, so this page does not rank the alternatives by toughness.
A Mohs Number Describes the Material, Not Your Ring
A published Mohs value belongs to the pure material. In a finished ring the metal, the girdle thickness and the setting decide as much as the number does. One cleaning instruction covers every stone here: most rings can be cleaned at home with warm water, mild soap and a soft brush (GIA 4Cs, Complete Guide to Engagement Ring Settings, 2026), and GIA warns that ultrasonic vibration can shake gems loose or damage gems set with their girdles touching (GIA 4Cs, Ultrasonic Cleaners for Gems, 2015).
Which Diamond Alternative Fits Your Life?
Alternatives to diamonds for engagement rings come down to hardness, budget and what the stone actually is; what couples spend on an engagement ring sets the budget side.
| If this is you | Consider | Why | Source |
|---|---|---|---|
| You want the hardest stone that is not a diamond | Moissanite | GIA puts it at 9.25 on the Mohs scale, second only to diamond | GIA |
| You want a colorless natural gem for daily wear | Colorless sapphire | GIA puts it at 9 and calls it well suited to everyday wear | GIA |
| You want color and still want hardness | Ruby or colored sapphire | Both score 9 on GIA’s figures, which GIA calls ideal for everyday wear | GIA |
| You want a soft pink or green stone and accept more care | Morganite or emerald | GIA puts both at 7.5 to 8, softer than diamond, so a protective setting helps | GIA |
| Your budget is the binding constraint | Cubic zirconia | GIA says CZ often costs less than 5% of a comparable diamond, at 8 to 8.5 hardness, with scratches and abrasions accumulating over time | GIA |
| You work with your hands all day | A protective setting before a particular stone | GIA says chips happen when a girdle or point strikes something hard, and that bezels, partial bezels and V-shaped prongs protect vulnerable points and corners | GIA (2016) |
If your hands are busy all shift, start with the setting, as our guide to engagement rings for nurses does; engagement ring shapes compared then shows which carry exposed points.
Frequently Asked Questions
What Is a Poor Man’s Diamond Called?
No stone officially carries that nickname. People use it loosely for whichever look-alike is cheap at the time, most often cubic zirconia and sometimes moissanite, and it is a slang label rather than a material. Sellers cannot rely on it either, since FTC guidance expects a specific disclosure word next to the gem name.
What Is the Diamond Alternative Called?
The trade term is simulant. GIA uses it for materials that mimic the look without the composition, naming glass, moissanite and cubic zirconia as the common ones. On a price tag the FTC’s vocabulary applies instead: imitation, simulated, laboratory-created or [manufacturer name]-created, placed immediately before the gem name with equal conspicuousness.
What Looks Like a Diamond but Is Cheaper?
Moissanite and cubic zirconia are the two colorless stones sold for that resemblance, and GIA lists both among the common simulants alongside glass. Colorless sapphire and colorless zircon are also sold as colorless center stones, though they are natural gems rather than imitations of anything, and GIA rates them very differently for hardness.
What Is the Cheapest Diamond Substitute?
Cubic zirconia is the cheapest of the stones on this page: GIA says its cost is often less than 5% of a comparable diamond, which is why it remains an accessible option. Its trade-off is wear, since GIA records scratches and abrasions accumulating over time, colorless material yellowing, and colorless CZ being somewhat brittle.
Do Wealthy People Wear Moissanite?
No named, dated source measures what wealthy buyers put on their hands, so nobody can answer that honestly with data. What GIA does publish is that moissanite is one of the most popular alternative gemstones for engagement rings today, sits at 9.25 on the Mohs scale, and costs much less than a comparable diamond.
Sources
- Federal Trade Commission, eCFR, 16 CFR Part 23, Guides for the Jewelry, Precious Metals, and Pewter Industries, section 23.12, 2018, current as accessed 11/09/2026.
- Federal Trade Commission, eCFR, 16 CFR Part 23, section 23.25(b) and Note 1, 2018, current as accessed 11/09/2026.
- GIA, Diamond Alternatives: Engagement Rings, undated, accessed 11/09/2026.
- GIA, Jewelry Buyers Guide to Diamond Alternatives, undated, accessed 11/09/2026.
- GIA, An Introduction to Imitation Diamonds & Other Gems, undated, accessed 11/09/2026.
- GIA, Simulants, Moissanite and Lab-Grown Diamonds, undated, accessed 11/09/2026.
- GIA (Al Gilbertson), How to Protect Your Diamond from Chipping, 2016.
- GIA 4Cs, Ultrasonic Cleaners for Gems: What You Need to Know, 2015.
- GIA 4Cs, Complete Guide to Engagement Ring Settings: Types vs. Styles, 2026.
- GIA, Laboratory-Grown Diamond Report (LGDR) by GIA, undated, accessed 10/09/2026.