Uncut Diamonds: Before the Shine

March 27, 2020 – See the brown mineral that looks like a lump of dirt in the featured pictures? These are real diamonds, on display in our mineral case inside Discovery Center. Discovery Park guests who view them are often surprised that their appearance is not what they expected, but these are uncut diamonds, which means they aren’t reflected and shiny yet.

Diamonds can reflect light and shine with incredible beauty, but in order to do that, they must be cut into a shape with flat surfaces. Consider your mirror–it probably doesn’t have a curved surface. Puddles are much the same, since water can reflect light, but the more ripples and waves on the water surface, the less of the reflection you can see.

Diamonds, and many other precious stones, come out of the ground in all kinds of shapes, and frequently need to be cut so that they have flat surfaces to sparkle and shine.

Cutting a diamond is not easy. A diamond is so hard that another diamond is required to cut it. Of course, this doesn’t mean that diamonds are invulnerable to objects that are not diamonds – a diamond can be broken with a hammer, an industrial crusher or any object possessing enough force. Diamonds are unable to be cut or scratched without using another diamond, but they will eventually break just like any other mineral will break into pieces when subject to sufficient force.

Interestingly though, diamonds break in specific directions, called “cleavage planes,” which allow experts to predict how they will come apart and gemcutters to perform wonders. Some diamonds have been cut many times into smaller ones. For example, the Cullinan Diamond, the largest clear diamond in the world, was cut many times into nine major and more than 90 minor stones.

One thing that many people falsely believe about diamonds is that they last forever. Certainly this message is often repeated in advertisements, but diamonds, and other minerals and rocks, are always changing to fit their environment.

Consider a firefighter, underwater welder or astronaut: they wear protective gear in extreme environments, but not in their living room. When protection is not needed, they change into bluejeans, which are more comfortable than a spacesuit or diving gear. Rocks and minerals change to suit their environments, too. Geologists use the term “metamorphism” when rocks change due to heat and pressure into a new form to suit their environment.

Carbon, which makes up diamonds, is formed at ultra-high pressures, where it is stable many miles down in the extreme heat and pressures in the depths of our planet. However, when carbon is removed from that extreme heat and pressure that made it turn into a diamond, it continues, slowly but surely, to change into other substances. Given enough time, the diamonds on rings and necklaces will turn into other forms of carbon. This might take hundreds of thousands of years, but even a million years is less time than forever!

Make sure you come to the Natural History Gallery at Discovery Park of America and enjoy our diamonds, emeralds, fossils, rocks, and minerals, while they still look amazing.

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