Iron – One of the components of steel, and the go-to metal for tool and weapon makers throughout the ages, iron completes the list of the world’s strongest metals. Cast iron scores about 5 on the Mohs scale, and its yield and tensile strengths are about 246 and 414 Mpa respectively.

A diamond is undeniably hard but it’s brittle and not overly tough, so it will most likely shatter if struck by a bullet.

Diamonds are cut with specialized tools that make use of diamond tipped phosphor bronze or diamond dusted steel blades. Such tools are used to exploit the structural weakness of the diamond by grooving and striking along specific tetrahedral planes.

How to Destroy a Diamond

1. Smashing. Diamonds are one of the hardest gems, making them hard to cut, but they’re very fragile!
2. Oxygen. If you heat a diamond to 700 degrees Celsius in open air it will burn, because diamonds are made of carbon.
3. Fire.
4. Cleavage Planes.

You can crush a diamond with a hammer. Simple steel can be used to cleave a diamond along a flaw or its tetrahedral plane. Lasers or other diamonds can be used to “break” a diamond as well.

Lava is not hot enough to destroy diamond. In fact it’s typically less than a third of the temperature it would take to destroy a diamond.

any material that has a melting point higher than 2000 F will withstand lava. With the temperature of lava (That is, above ground and not magma, which is below ground) being between 1300 – 2200 degrees F, any alloy or material with a melting point above that will withstand contact.

Hardly any human has been killed by a lava flow – they are relatively slow-moving and while they can destroy huge tracks of farming land, houses, roads, and infrastructure, even on the most active volcanoes, you can outrun all the lava flows.