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One of the oldest debates in the world of gems and jewellery has been about the vocal distinction between diamonds and gemstones. Why are they always put into 2 different categories of ‘diamonds’ and ‘gemstones’ when much about them is quite similar? It is understandable that people often tend to use these 2 words interchangeably because, in their perspective, diamonds are gemstones.

Gemologically speaking, a stone is called to be of ‘gem quality’ when it fulfils three criteria:

• It is durable
• It is rare
• And it is beautiful

These 3 criteria differentiate just about any mineral found in nature that can be used in industrial purpose from the real ‘gem-quality’ stones. So does that make diamond a gemstone as well? Technically speaking, diamond is a gem-quality stone but is often kept aside from the category of gemstones. Here is a look at what creates this difference between diamonds and gemstones.

The Science Behind the Formation of Diamonds

A great way to get a better insight into the differences is to look at their composition. Gemstones are all formed when an element was trapped under the earth’s crust for billions of years and solidified together because of the heat and pressure that was put on them.

While other gemstones are often minerals formed by the crystallisation of compounds made with 2 or more elements with other trace materials that gives them their distinctive colours, diamonds are a little different. Diamonds are a crystalline form of carbon, which also explains why diamonds are so durable. In comparison, Ruby is a crystalline form of Aluminium Oxide also known as corundum. The distinct red colour in ruby comes from the trace quantities of chromium in the crystal. If the trace minerals were titanium and iron, the colour would have turned blue and the stone would have been called a Sapphire instead.

The Difference

‘Gem-stones’ is a wider term that represents all gem-quality stones. However, the distinction between coloured gemstones and diamonds comes from their internal composition. Now, this may beg the question of whether coloured diamonds also fall under the category of coloured gemstones. The answer is still the same. Coloured diamonds are actually coloured gem-quality stones, but they do not fall under the category of coloured gemstones because they still follow the simple rule of being composed entirely of carbon, with trace elements that add a tinge of colour to them.