Natural Diamonds

How they are formed

Diamonds are formed over billions of years from a combination of extreme heat and pressure within the earth. They are made from carbon and are the hardest known substance on earth.

Where they're mined

India is believed to be the oldest producer of natural diamonds, but many other countries have been historically mining gemstone quality diamonds for hundreds of years. Brazil, South Africa, Russia, the Democratic Republic of Congo, Botswana, Canada and Australia have all contributed to the world's diamond supplies between the mid 19th century to present day, respectively. 

Grading system

Diamonds have the most structured, universally respected grading system of all gemstones. Strict quality indicators exist across factors such as the stone's natural colour, clarity and fluorescence, and the resulting quality after being cut, such as its polish, symmetry and overall proportions, in addition to the quality of the cut itself. These quality indicators affect the value of the stone, and are important to understand when purchasing a diamond.

Most people recognise the 4C's, a simplified grading system developed in the 1950's by the Gemological Institute of America (GIA) to make the selection process for individuals easier by narrowing down the quality factors to the four most important in relation to the overall aesthetic quality of a diamond. These are Carat, Cut, Colour and Clarity.


Natural diamonds occur most commonly as yellow or brown in colour, so colourless or 'white' diamonds are more valuable as they are rarer. Coloured diamonds can also be highly valued; colours such as pink and blue are held in particular esteem as they are extremely uncommon in nature, and many diamonds are chemically treated to obtain these desired hues. At NMJ we work only with naturally coloured diamonds to ensure the highest quality, authentic stones.


There are a variety of certification bodies that provide certificates of authenticity within the diamond industry. For our Bespoke and One of a Kind pieces, we work exclusively with GIA certified mined diamonds (over 0.30ct), as these are regarded as the highest quality, most accurately graded diamonds in the world. Each diamond comes with its own paper certificate listing the individual specifications of the stone and whether the stone as received any heat treatment. It also bears a unique laser inscribed serial number on the girdle of the diamond to ensure that the diamond, and its unique characteristics, can be identified and traced.


Natural diamonds are those that have not been treated in any way to alter their colour. They are the highest valued diamond-type within the jewellery industry. Historically they the most prestigious of all precious gemstones and, when stringently certified through the GIA, they maintain their value over time.