Last Updated: April 2026
TL;DR:
- A real diamond rates 10/10 on the Mohs hardness scale — the only material that can scratch a diamond surface is another diamond. Steel, concrete, and ceramic all rank 4–8, far below diamond’s threshold.
- Hardness and toughness are different properties. Diamond is the hardest natural substance, but it can chip or cleave under a sharp blow at specific grain orientations — because toughness (resistance to fracture) is only moderate.
- Lab-created diamonds and natural black diamonds share the same Mohs 10 hardness as mined white diamonds. Fake stones (CZ rates 8–8.5, moissanite 9.25) can be scratched by real diamond.
Diamond’s scratch resistance is one of the most misunderstood properties in jewelry. Buyers assume hardness means invincibility — it doesn’t. I’ve worked with diamond tools and diamond jewelry for over 20 years, and the distinction between hardness and toughness matters a lot when choosing how to wear and store your diamond pieces. For context on how diamond durability compares to another hard metal, see whether platinum scratches easily — platinum is harder than gold but still ranks only 4.5 on the Mohs scale.
Can a Real Diamond Be Scratched?
A real diamond cannot be scratched by any natural material except another diamond. At Mohs 10, diamond is the hardest naturally occurring substance on Earth. Steel is 4–4.5. Quartz (the most common mineral in dust and sand) is 7. Corundum (sapphire/ruby) is 9. Nothing below Mohs 10 can scratch a diamond surface — only another diamond can leave a mark.
This is why diamond-tipped tools are used to cut everything from glass to concrete. The hardness is absolute — in any test where diamond meets a softer material, the softer material gets scratched, not the diamond. According to GIA’s gemological standards, hardness on the Mohs scale isn’t linear: the difference between corundum (9) and diamond (10) is many times greater than the difference between talc (1) and corundum. That single step from 9 to 10 represents a massive leap in scratch resistance.
However, this scratch resistance applies to the diamond’s surface mineral structure. A diamond can still chip or cleave — the difference matters and we’ll cover it next.
What Is the Difference Between Hardness and Toughness?
Hardness measures resistance to scratching; toughness measures resistance to fracture. Diamond scores 10/10 on hardness but only “good” (not exceptional) on toughness. This means a diamond will never get scratched by metal, but can chip or shatter if struck at the right angle with sufficient force — particularly along its cleavage planes, where the atomic bonds are weakest.
Diamond has four natural cleavage planes — directions where the crystal structure bonds are weakest and the stone will split cleanly if struck parallel to those planes. This is actually how diamond cutters shape rough diamonds: they study the grain and use a sharp steel blade (or a laser) to cleave along those exact planes. If a diamond ring is dropped onto a hard surface at an unlucky angle, the impact could find one of those cleavage planes and chip the stone. The chip isn’t a scratch — it’s a fracture. Different problem, same jewelry damage.
Can Diamonds Be Scratched by Metal?
No — metal cannot scratch a diamond. No metal in common use, including hardened steel (Mohs 4–4.5), tungsten carbide (8.5–9), or titanium (6), reaches the hardness threshold needed to abrade diamond. When a metal object contacts a diamond, the metal gets scratched — not the diamond. This is why diamond-tipped drill bits can cut through steel.
What you might see on a diamond after contact with metal is residue — the metal leaves a smear on the diamond surface rather than a scratch. This smear is the softer material being transferred onto the harder one, not a gouge in the diamond’s crystal structure. The smear wipes off with a gentle cloth. For a similar hardness comparison with a common ring metal, see how platinum holds up to daily wear.
Can Diamonds Be Scratched by Concrete?
Concrete itself cannot scratch a diamond — concrete’s hardness varies but sits around 4–7 on the Mohs scale depending on aggregate composition. However, concrete aggregate often contains quartz (Mohs 7) or corundum particles, which still fall short of diamond’s 10. The diamond will scratch the concrete, not the reverse. That said, a sharp concrete edge could still chip a diamond if the impact is forceful and hits a cleavage plane.
This is the distinction most people miss: scratching and chipping are different failure modes. A diamond won’t accumulate surface scratches from dragging across concrete, but dropping a diamond ring onto a concrete floor could chip it. The concrete isn’t scratching the surface — it’s delivering impact force at an angle that might split along a cleavage plane.
Can Black Diamonds Get Scratched?
Natural black diamonds have the same Mohs 10 hardness as colorless diamonds — they cannot be scratched by any material except another diamond. However, black diamonds are often polycrystalline (many small crystal fragments bonded together rather than one continuous crystal), which gives them a slightly different structural profile. Their surface scratch resistance is identical to white diamond; their cleavage behavior differs because there’s no single large cleavage plane in a polycrystalline structure.
This polycrystalline structure makes natural black diamonds more difficult to cut and polish — the many crystal orientations mean there’s no single grain direction to follow, requiring diamond dust rather than directional cleaving. Black diamond’s origins are still debated (some hypotheses suggest meteorite or even interstellar origin), but their hardness properties are well-established at Mohs 10.
Can Lab-Created Diamonds Get Scratched?
Lab-created diamonds cannot be scratched by anything except another diamond — they have identical chemical, physical, and optical properties to mined diamonds. Both are pure carbon in the same cubic crystal structure. The only difference between lab-grown and mined diamond is the origin, not the hardness or scratch resistance. A lab-created diamond at Mohs 10 resists scratches exactly as a mined diamond does.
This is worth stating clearly because of the common confusion with diamond simulants — fake stones that look like diamond but have different composition. Cubic zirconia (CZ) rates 8–8.5 on the Mohs scale; moissanite rates 9.25. Both can be scratched by real diamond (lab or mined) and will show surface scratches over time from contact with quartz dust and other common abrasives. Lab-created diamond simulants are not lab-created diamonds — they’re different materials. If you’re uncertain whether a stone you own is real diamond, see how diamond testers work and what they actually measure.
Can You Scratch a Diamond with Sandpaper?
Standard sandpaper cannot scratch a diamond. Sandpaper abrasives are typically aluminum oxide (Mohs 9) or silicon carbide (Mohs 9–9.5) — both fall short of diamond’s 10. The sandpaper will wear down before it marks the diamond surface. Diamond-embedded sandpaper (used in industrial lapping applications) is a different product and can abrade diamond surfaces, but it requires actual diamond as the abrasive.
This is also why diamond polishing wheels use diamond dust rather than conventional abrasives — no other material is hard enough to shape and polish diamond’s surface. The polishing process removes material from the diamond using diamond particles harder than the base stone, which is why diamond cutters work in grain-specific orientations. For how diamond value holds up long-term, see our analysis of why diamond resale value drops so sharply — useful context if you’re considering diamond as an investment.
The Bottom Line
A real diamond — mined or lab-created, white or black — cannot be scratched by any common material. Metal, concrete, sandpaper, and everyday abrasives all sit well below Mohs 10 and will leave no mark on diamond. What diamond is vulnerable to is impact: a sharp blow at the right angle can chip or cleave the stone along its natural grain planes. Protect your diamond from hard knocks, especially on corners and edges where the prongs hold the stone. Don’t worry about scratches from everyday wear — worry about drops. And if you’re buying diamonds and want to verify authenticity before wearing, see whether Costco diamonds come with GIA certification — certification is the most reliable way to confirm what you’re actually buying.
Frequently Asked Questions
What is the hardest thing that can scratch a diamond?
Only another diamond can scratch a diamond surface. Diamond rates 10/10 on the Mohs scale — the maximum. No natural material exceeds Mohs 10. In industrial settings, diamond-embedded abrasive wheels and lapping compounds (which use diamond dust as the cutting medium) are used to shape and polish diamond, but the abrasive doing the scratching is still diamond. Synthetic nanodiamonds can also abrade diamond surfaces at the microscopic level.
Can a diamond scratch a sapphire?
Yes, easily. Sapphire (corundum) rates Mohs 9 — one full step below diamond on the scale. A diamond will scratch sapphire’s surface on contact. This is relevant for jewelry storage: storing a diamond ring loose with sapphire earrings in the same compartment will result in scratches on the sapphire. Always store diamond jewelry separately from other gemstones, even other hard stones like sapphire and ruby.
Can sweat or chemicals damage a diamond?
No chemical damage in any typical household scenario. Diamonds are chemically inert at room temperature — acids, solvents, cleaners, and even hydrofluoric acid won’t etch or damage the diamond crystal. What chemicals can damage is the metal setting (gold or platinum can be affected by chlorine bleach) and any CZ or treated stones in the same piece. The diamond itself is chemically stable under all normal wear conditions.
Can two diamonds scratch each other in a jewelry box?
Yes — and this is a real storage concern. Diamonds can scratch other diamonds because they’re the same hardness. If you store diamond rings or diamond earrings loose in the same box, the facets will contact each other and create surface abrasion over time. Store each diamond piece in a separate pouch or compartment. This is why jewelry pouches and divided boxes exist — the risk isn’t from external materials but from diamond-on-diamond contact.
Tiger is a fashion&jewelry lover. He is also a fashion jewelry manufacturer that help thousands of small business to grow and also do business with some big fashion jewelry brands. He is a truly metal expert and he will share some information you are looking for.