Introduction

Let's begin with an introduction to diamonds. This video discusses diamond's chemical composition and crystal structure and explores some of their most impressive properties.



Transcription

Diamonds make exceptional gemstones. They possess properties which give them the ability to return most of the light that enters them, resulting in a scintillating display of fire (dispersed light) and brilliance (white light). Diamonds have become the most popular gem for use in jewellery as the unparalleled hardness of diamond keeps it looking as perfect as the day it was cut. 

Diamonds have been used as a gemstone for over 2500 years and for a similar amount of time they have also been used as an abrasive due to their hardness. Apart from being beautiful it turns out that diamond is one of the most useful materials in the world.

What is diamond?

Diamond is a mineral; a mineral is a crystalline inorganic material that formed in nature.

Diamond is composed from nearly 100% carbon. Graphite is another mineral made out of of pure carbon, but these two materials are very different from one another with diamond being the hardest natural material on Earth and graphite being one of the softest.

So what makes diamond so special? 

The answer lies within its crystal structure. Let's focus on the carbon atoms within diamond and how they are bonded.

A Carbon atom has a valency of four; meaning it has four electrons in it's outermost shell.

In diamond, each atom is bonded to another four carbon atoms and every electron is tied up in a bond. These are all in a tetrahedral co-ordination where each bond is of equal length and strength.

Each atom shares an electron with it's neighbouring atom - these are called “covalent bonds” and are the strongest bonds possible. The bonds organise the atoms in a cubic crystalline structure which repeats itself over and over.

The atoms in diamond are more tightly packed together than in any other material on Earth. It's this density and strength of the bonds that give diamond it's extraordinary properties; classifying it as a "supermaterial".

What are diamonds super material properties?

Diamonds are renowned for being the hardest natural material known to manThey are the best thermal conductors and experience little thermal expansion. They are also chemically inert to other materials in most environments.

These properties make diamonds extremely valuable for industrial applications as use as abrasives as they can easily cut through most other materials.

The demand for industrial diamond is the primary reason for the creation of laboratory-grown diamond, which was first created in the 1950’s.

The demand for this product [industrial diamond] is so high that nowadays the number of diamonds used for industrial applications far surpass the amount used in jewellery each year.

Diamonds also have a whole host of other supermaterial properties and with advancements in the growth of laboratory grown diamonds; new applications are being experimented with as we speak that were never been possible before.

Qualities and sizes suitable for fashioning lab-grown diamonds have been available since the 1970’s, however, it has only been in the past 10 to 20 years that these have been grown in large enough volumes to allow them onto the commercial gemstone market.

Gem-quality laboratory-grown diamonds are the focus of this course. Before we dive in to this fascinating subject - let’s start with definitions of natural and laboratory grown diamonds. 

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