A diamond can be scratched, but only by another diamond. The Gemological Institute of America rates diamond 10 on the Mohs scale, the highest point, and describes it as so hard that only a diamond can scratch a diamond. That is a measure of resistance to scratching, not a promise that the stone is indestructible. A diamond can still be chipped, and it can also scratch the metal around it if it becomes loose in the setting.
What hardness does and does not mean
The Mohs scale ranks how well a mineral resists being scratched by another. GIA is clear that the steps on the scale are not evenly spaced: diamond is only one number above corundum, which includes ruby and sapphire, but it is many times harder. Hardness is also not the same as toughness. GIA describes toughness as how well a gem survives an impact, or resists breaking, chipping or cracking. Diamond is the hardest gemstone, but not necessarily the toughest, and it can be cleaved or fractured by a hard blow. Our guides to the Mohs hardness chart and to cleavage and chips set that distinction out in more detail.
The setting, and other jewellery in the same box
GIA also notes that a diamond can scratch the precious metals used for settings, and that a diamond which is loose in its setting can wear through a claw over time. A periodic check of the claws is worthwhile, which our guide to care and maintenance covers. In a jewellery box, a diamond can scratch a softer gem beside it. GIA's advice is not to store a diamond next to other gems, and to take care with pieces that sit together. Our guide to polish and symmetry explains the finish of the facet surfaces themselves.
How we talk about this when we make a ring
We look at the stone and the setting with you on a video consultation, and nothing is made until you approve the design and the stone in writing. A 70 percent deposit is paid then, making time is 5 to 6 weeks, and the ring is UK hallmarked before insured, tracked FedEx delivery. A well fitted setting, and ordinary care, matter more than any idea that a diamond cannot be marked at all. If you would like to talk through a stone or a setting, get in touch or browse the diamonds we can source.
Frequently asked questions
Can a diamond be scratched?
Yes, but only by another diamond. GIA rates diamond 10 on the Mohs scale, the highest point, and describes diamond as so hard that only a diamond can scratch a diamond. Hardness is resistance to scratching, not a promise that the stone cannot be chipped.
Does that mean a diamond cannot be damaged?
No. Hardness and toughness are different. A diamond resists scratches very well, but it can still be chipped or cleaved by a hard blow. Our guide to cleavage and chips explains that difference.
Can a diamond scratch the metal of a ring?
Yes. GIA notes that a diamond can scratch the precious metals used for settings, and that a diamond which has become loose can wear through a claw over time. That is one reason a periodic check of the setting is worthwhile.
Should diamonds be stored against other gemstones?
GIA advises that you should not store a diamond next to other gems in a jewellery box, because the diamond could scratch them. Keeping pieces apart, or in separate pouches, is the safer habit.