The blue diamond adopts its luxurious colour at an early stage, when boron first appears. The more boron, the more intense the colour. Very occasionally, due to the additional presence of hydrogen a greyish blue appears.

Blue diamonds generally come from South Africa, while a small number of deep blue diamonds are found in Central Africa, Brazil & Borneo. Historically, blue diamonds have been found in India and metallic blue diamonds have been found in the Argyle mines in Australia. In November 2014, a 9.75 carat blue diamond, the Mellon Blue, sold for a staggering $32.6 million at Sotheby’s in New York, before being renamed the Zoe Diamond.

A pink diamond is formed under astounding pressure under the earth’s surface when its crystal lattice deforms.

Fancy coloured diamonds, including pinks, generate even higher returns than colourless diamonds. Rare pink diamond prices have increased by 443 percent in the last 10 years and in some cases can reach 50 times the price of a colourless diamond equivalent. The largest mine for pink diamonds is the Australian Argyle mine, although smaller quantities are also mined in Borneo, Guinea, Brazil, Angola and South Africa.

Fiery yellow coloured diamonds are created thanks to the presence of nitrogen.

Star Diamond prides itself on assembling some of the world’s most unconventional and unique diamonds, such as an exceptionally rare lime diamond. 

Yellow diamonds are mostly mined from Brazil, Russia, Australia and Africa. The more intense colours are typically found in South Africa.

Orange and brown diamonds, often called cognac, champagne and even cinnamon diamonds, are formed by the presence of nitrogen.

A pure orange colour is the rarest colour of this category and is caused by a combination of nitrogen atoms and structural deformities. 

Brown tone diamonds are mined in Australia, Borneo, Brazil, the African continent and Russia. Orange diamonds are found in South Africa, the Democratic Republic of Congo and Russia.

Green diamonds colour is derived from exposure to gamma rays way below the earth’s surface over an extensive period of time, perhaps millions of years. 

They are among the rarest diamonds in the world.

Most green diamonds are sourced from British Guyana, Borneo, Brazil and Central Africa.

Diamonds were formed by nature at least 990 million years ago and many are billions of years old.

Colourless diamonds are graded from the colour D to the colour Z, colour D being the finest colourless grade. There are four qualities to a diamond, its cut, colour, carat and clarity. As Henry Kissinger once said: “A diamond is a chunk of coal that did well under pressure.”

Emeralds are mineral beryls with a hexagonal crystal formation. Their green colour is due to traces of chromium and at times vanadium.

Much like a diamond, emeralds are graded by the four Cs, colour, cut, clarity and carat. Colour is by far the most significant criterion, but clarity is not far behind. For an emerald to be considered a top gem it needs a pure green hue as well as optical transparency.

Emeralds routinely have natural surface breaking fissures and inclusions, sometimes described as jardin, meaning garden, alluding to their natural mossy appearance.  A vast majority of emeralds are treated with fracture filling oil which enhances their clarity. Two emeralds that appear visually identical can differ quite substantially in their value depending on their treatment levels. Unlike a diamond, flawlessness in emeralds is judged by the eye and not a loupe. It is advisable to insist upon certified emeralds.

There are predominantly two countries producing large quantities of emeralds, Colombia being by far the world’s largest producer of emeralds, Zambia being the other.

Sapphires are mineral corundums with a formula of aluminium oxide and a trigonal crystal formation.

They have a remarkable hardness to them and are among the hardest minerals after the diamond. They come in many colours -  blue, purple, pink, yellow, orange and green. Their value depends on their colour, quality, size, geographic origin and scarcity.

Known for their voluptuous silky characteristics due to their natural silk deposits, sapphires of high calibre, such as Kashmir sapphires are becoming increasingly rare, and their value is on the rise.  Padparadscha sapphires, which have a natural pink orange hue, mostly found in Sri Lanka, have become one of the most valuable kinds of sapphires as their rarity increases.

Insisting upon certified sapphires is important to verify whether the gem is heat treated or not.

Sapphires are mined from Ceylon (Sri Lanka), with dwindling quantities in Burma and even less in Kashmir.

Similar to sapphires, the ruby is also a mineral corundum, with a formula of aluminium oxide and chromium.

As hard as the sapphire, the ruby is among the hardest gemstones after the diamond. The chromium is what gives it its pink or red tint. Monetary values of rubies are primarily determined by their colour, applying the grading parameters of the four Cs. The  most valuable rubies are the brightest reds often labelled pidgeon blood rubies.

All natural rubies have inclusions and imperfections, which is why almost all rubies are treated in some way, with heat treatment being the most common method. Rubies of excellent quality which are completely untreated are therefore far more valuable.

The Mogok Valley in Burma has historically produced some of the world’s finest rubies. Today excellent quality rubies are sourced from Mozambique and Tanzania where their value is rising.