How durable are rubies?

Rubies are unusually durable, sitting at 9 on the Mohs scale, so they handle scratching extremely well and end up being really ideal for daily use in rough situations like engagement rings.

As a kind of mineral corundum, ruby is beaten in sheer hardness only by diamonds. Also, rubies have great toughness, which makes them very resistant to chipping or breaking from physical impact, and that blend of hardness with solid structural integrity means they can survive the pressures of everyday life for years and years, generations even.