Blog - Diamond Beauty (2) - ‘Life’.

Let’s look at light reflected from a diamond. If you are wearing a diamond (lucky you!) or can see a diamond near you, take a very close look at it now. Without moving the diamond, see if you can see how ‘shiny’ it is, how light is reflected from its surface. 

When scrutinising the diamond can you discern its flat surfaces, called facets? There are many having various shapes, varying sizes and are arranged in a symmetrical pattern called the facet arrangement. We shall see later the sizes, pattern and angles between facets contribute greatly to the beauty of diamond. 

You see your face when looking in a mirror because all the light falling on it from your face is reflected from the flat mirror surface back to your eyes. When light falls on a diamond almost all enters the gem through the top  (crown) facets but a surprising amount doesn’t, it’s reflected back. Some of this reflected light reaches your eyes; you see the facets as shiny surfaces.

How much light is reflected from a gem’s facet in relation to the amount of light falling on it is called reflectivity. Diamond has many superb characteristics as a gem, one of them is its high reflectivity. So high, that when light falls on a diamond facet almost a fifth doesn’t enter the gem, it is reflected back to our eyes creating the ‘shininess’ so loved by many diamond admirers. 

Let’s use the word ‘life’ in place of  ‘shininess’.  We shall see later that the size of the largest facet on top of a diamond, the table facet, greatly influences the amount of ‘life’ of a diamond.

You may have heard the word lustre. Gemmologists use it to describe the appearance of a gem’s surface when it reflects light. Diamond has such a high lustre compared to other gems it has its own unique description: ‘adamantine’ lustre. Most other gems have a glass-like or ‘vitreous’ lustre. The unique lustre of diamond is due in part to its extreme hardness; no other gem comes close to being as resistant to being scratched by other materials. Its superb hardness means it takes an extremely flat facet surface when cut and polished from the uncut ‘rough’ crystal. A very flat facet makes for a great reflecting mirror surface.

Summary:

Diamond is so shiny due to its superb physical (hardness) and optical (reflectivity) properties. Shininess or ‘life’ is seen as light reflected off the crown facets of a diamond. Life is just one component of the famed brilliance of diamond. Most of the light falling on a diamond enters the gem. We shall consider this in the next blog.