The concise A-Z encyclopaedia of gemstones

The concise A-Z encyclopaedia of gemstones

Alexandrite - June birthstone


Alexandrite is famous for the fact that it can change colour, appearing bluish-green in daylight and reddish-pink by indoor lamplight. The value of this stone increases with the distinctness of the colour shift. Alexandrite was first discovered in the Ural Mountains in the early 19th century but it is now mostly produced in Sri Lanka, East Africa and Brazil.

Amethyst - February birthstone


Amethyst has long featured in many tales, myths and religious texts since ancient times. Part of the appeal of amethyst is that it can be found in a wide array of shapes and sizes, making it accessible to even the smallest collector. It also works well with all metal types and offers a neutral accompaniment to almost any colour.

Aquamarine - March birthstone


Aquamarine derives its name from its close resemblance to the deep blue ocean. Aquamarine was said to have a calming effect on married couples in mythology, making it very popular as an anniversary gift. This stone comes in a range of hues from pastel blue to greenish-blue. The darker shades are far rarer and hence more valuable.


citrine 2

Citrine is an affordable stone that gets its name from the French word for "lemon." It is found in a range of hues from citrus yellow to orangey-brown. In ancient myth citrine was thought to provide defence against snake venom and evil intentions but in contemporary culture it is viewed as the "merchant's stone" and commonly held as a bringer of wealth and happiness.

Diamond - April birthstone


Diamonds were created under enormous pressures, over a hundred miles below the surface, more than a billion years ago. At 10 on the (1-10) Moh's Scale, they are the hardest of all gems. De Beers made them the dominant gem for over 100 years, although coloured gemstones are now resurgent. The 4 C's (cut, colour, clarity & carat) are key to assessing the value of a diamond and the principle benchmark lab for these stones is the GIA (Gemmological Institute of America).

Emerald - May birthstone


Green has long been associated with good fortune and fertility and emerald is said to be the stone of Venus. Famed as the gem of choice for Cleopatra in ancient Egypt, many mummies were actually buried with them for eternal youth. The depth of colour is key to the value of an emerald and the finest specimens are produced in Colombia. Nearly all emeralds are included and some are treated with cedar oil to fill small surface reaching fissures. Trusted laboratory certificates, from reputable sources such as CDTEC in Colombia and SSEF and Gübelin in Switzerland, are essential to ensure an accurate assessment their true provenance, treatment and natural colour.

Fancy coloured diamonds


Coloured diamonds are fantastically rare gemstones, created by unique chemical and physical conditions in the earth's crust. The main primary colours are pink, blue, yellow, orange, green, red and brown, although many combinations of these primary can be found, such as orangey-pink for example. The most important factor when it comes to the pricing of coloured diamonds are their colour intensity, usually measured from "vivid" to "faint." The rarest colour is red and it is interesting to note that a flawless, vivid red, round cut diamond is the most intense manifestation of wealth on the planet! After red, pink and blue are the most sought after, followed by green, then orange, yellow and brown.

Garnet - January birthstone


Garnet comes in a spectrum of colours, from deep red to vibrant green, orange and brown. In ancient mythology garnet was said to protect travellers from accidents and as such was often carried by them for good luck. The Romans used garnet rings to act as a stamp to create a seal on important documents, a practical use for the stone that was continued by scholars and monks for many centuries across Europe.



The use of jade in Chinese jewellery can be traced back as far as five thousand years. Jade was revered for centuries and it can be found in many royal tombs of the ancient Chinese dynasties. This stone is renowned for its smooth, glassy appearance and it is also found in hues of pink and yellow. Most jade pieces are flat and disc shaped with a hole in the centre, known as a "pi," which are often mounted on a necklace.

Lapis Lazuli

Lapis Lazuli

First discovered over 2,500 years ago Lapis Lazuli, or "blue stone," was used to create the vibrant blue colouration in Renaissance art work. Its microcrystalline composition is sometimes freckled with beautiful golden pyrite inclusions that give it a unique 'sparkle' or scintillation. Over the centuries Lapis Lazuli has been used as an aphrodisiac and as a medicine by many civilisations since Roman times.



Moonstone owes its name to Roman mythology, in which it was thought to have been formed from frozen moonlight. It can be found in a range of hues from colourless to pink, green, yellow, brown and gray and from transparent to translucent. In its most valuable form, it has a bluish sheen and a very high clarity and its rarest derivative is "rainbow moonstone," which displays a range of colours from pink and purple to yellow, peach and blue. It is produced in India and Madagascar and fine specimens are extremely rare.



Morganite, named after the famous American industrialist JP Morgan, is a enchanting pink stone. It is well renowned as a versatile gem that compliments all skin tones and metal types, including rose gold, yellow gold, white gold, silver and platinum. Its colour is best described as an infusion of shades of pastel pink, apricot, bright fuchsias and lavenders.



When most people consider onyx they tend to think off the black variety but in fact it comes in a range of colours including white, red, reddish brown as well as black. Sardonyx is a variety of onyx that is reddish brown in appearance with lighter reddish bands (pictured above).

Opal - October birthstone


Each opal displays a unique colouration, which identifies it like a fingerprint. Its colour changing qualities make it highly versatile and it can be worn with a range of outfits. It is the breadth of its spectrum of colour that determines its price. Some rarer examples include the black opal of Australia's Lightening Ridge but the more common varieties are found in many parts of Africa.

Paraíba tourmaline

Paraiba tourmaline

Remarkably paraíba tourmaline was only discovered less than 35 years ago but it has since risen to become one of the most valuable gems in the world. Its dazzling, vivid blue to greenish-blue colouration is unique to this stone and it derives its name from the site of its discovery in Paraíba state, north east Brazil. The most valuable examples are produced in Brazil, although some African tourmalines of similar colour have adopted the name 'paraíba' tourmaline.

Pearls - June birthstone


Pearls have been an important part of the jewellery trade for millennia. In Persian mythology they were said to be the "tears of the gods" and they were also especially revered by the ancient Chinese, who believed they were created by the Moon. Pearls are unique in that they are the only gemstone created inside a living organism. Pearls are found in both freshwater and saltwater varieties but the natural specimens are significantly rarer (and more valuable) than cultured (manmade) examples. Cultured pearls come in an array of colours, from white to green, gold, gray and black and there are four main types: Akoya; South Sea; Tahitian and Freshwater. Each have unique qualities.

Peridot - August birthstone


Peridot is unusual among gemstones in that it can only be found in one colour, the distinctive lime green you see above (although some yellowish green and brown stones purport to be peridot). Most peridot is produced in Arizona, USA but it is also found in Pakistan, Myanmar and China. Most examples are under 3 carats, when cut and polished, and specimens over 5 carats are rare. In some cases they can be found in sizes of 10-15 carats or more and these stones are actually surprisingly reasonably priced in comparison to other coloured gems of comparable size.

Rubellite (red) tourmaline


Rubellite tourmaline comes in a combination of vibrant pink and ruby red, sometimes with a hint of violet. According to the International Coloured Gemstone Association (ICGA) true rubellite shines with equal intensity in both artificial and natural light, although there is some disagreement as to the any true distinction between rubellite and red tourmaline. Its vibrant red colouration conjures emotions of passion and energy.

Ruby - July birthstone


Rubies have been part of the treasuries of monarchs and wealthy individuals for many centuries. Derived from corundum, ruby is effectively 'red' corundum and other (non red) stones of the family are termed sapphire. Rubies can be found in a spectrum of red hues, from orangey-red to bluish-red and purplish red. Most prized of all are the Burmese rubies found in the Mogok Valley in Myanmar (Burma). The type of deep red stone found here is often referred to as "pigeon's blood" which, counter intuitively, refers to the colour of a white pigeon's eye rather than its blood.

Sapphire - September birthstone


The etymology of sapphire lies in the Greek for 'blue' and it is for this reason these stones are always strongly associated with that colour. So called "royal blue" sapphires are the most valuable. However they are in fact found in almost every colour of the rainbow, notably pink, yellow, orange, peach and violet. Padparadscha sapphire are a rare type of pink-orange corundum that are highly sought after. Akin to their sister stone, ruby, they are corundum and are in fact any colour of corundum other than red (which is a known as a ruby). The most valuable stones come from Kashmir, where the mines ceased production over 80 years ago. Today they are mostly produced in Myanmar, Sri Lanka, East Africa and Australia.

Spinel - August Birthstone


For many centuries spinel has often been confused with ruby and ancient Sanskrit writings referred to it as the "daughter" of ruby. Spinel is actually rarer than ruby but they can sometimes be found in very large carat sizes. Although most spinel is red, it can also be found in orange, purple, pastel pink and very occasionally in blue. The most prized stones are Burma spinel, in particular the pink variety with a tinge of orange.

Tanzanite - December birthstone


Tanzanite is unique in that it can only be found in the foothills of Mount Kilimanjaro, Tanzania, East Africa. It is revered for its velvety blue hue with a tint of purple. Tanzanite can be cut into almost any shape and it is found in a large range of carat sizes and blue tones - very rarely is it pure blue. Smaller examples usually display lighter tones and a hint of lavender, whereas larger stones are typically a deeper and richer shade of blue.

Topaz - November birthstone


Topaz can be found in the full range of colours, as well as in colourless form. In its most valuable guise it is pink or 'sherry' red, sometimes referred to as 'imperial' topaz when it also has a tinge of orange and pink. Blue topaz was once the rarest but it is now the most frequently found, due to colour enhancement techniques. In ancient Greco-Roman tradition, topaz was associated with the sun god and it was thought to have divine healing properties.

Tourmaline - October birthstone


Tourmaline literally means "mixed stone" so it may come as no surprise that it is available in a huge array of colours, often within the same gemstone. It is the bi-colour or tri-colour stones that fetch the highest prices. Watermelon tourmaline are examples that display green, pink and white colour bands in the same stone. In keeping with its namesake it is often cut into 'slices' with a pink centre, surrounded by a white ring and a green outer edge.

Turquoise - December birthstone


Turquoise is one of the oldest recorded gemstones on earth, adorning the pharaohs of ancient Egypt and many of the native peoples of the Americas thousands of years ago. The more intense the blue, the more valuable the stone but most turquoise contains veins or other material that are usually black, brown or yellowish-brown. This phenomena is sometimes referred to as the 'matrix' or the 'spider's web' when they form an intricate pattern.

Zircon - December birthstone


Zircon is famous for its vivid blue variety but it is also found in hues of green, red, yellow, brown and orange, among others. It is becoming increasingly popular because it is unusual in that it is both rare and affordable. Some collectors are building 'rainbow' sets containing a zircon of each colour in the spectrum and it is certainly a gemstone to watch as its price in the future may continue to grow apace.

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