Diamond Facts

Around 30% of the diamonds mined worldwide are gem-quality.

The historic Cullinan diamond, found in South Africa in 1905, weighed an astounding 3,106 ct. It was cut into a total of 105 diamonds of exceptional colour and clarity.

Diamonds can be burned. To burn a diamond, it must be heated to between 1290-1650 degrees Fahrenheit. House fires and jewellers’ torches can sometimes reach that temperature.
Diamonds come in all colours of the rainbow. For natural coloured diamonds, blue, green, orange and red are the rarest; yellow and brown are the most common.

Diamond weight is measured in carats, the word Carat is derived from keration, the Greek name for the carob tree whose seed was used for centuries as the standard of weighing precious stones. As the seeds can vary slightly in weight, in 1913 carat weight became metric; one metric carat is equivalent to 0.2 grams, or 0.007 ounces.
Cullinan rough & Pear shape polished

Rough Diamonds

When natural diamonds are found in the earth, before they are cut and polished, they are called rough diamonds and still have their outer ‘skin’.

They can be discovered in a variety of shapes from cubes to octahedrons (imagine two pyramids joined together at the base). All started life deep within the earth’s mantle between 720 million to 3.5 billion years ago, created under extreme pressure and high temperatures.

The exact conditions of their creation, as well as those they experienced during their long journey to the earth’s surface through volcanic activity, shape their unique characters and colours. For example, pressure can distort their atomic lattice to create a pink rough diamond, or when saturated with nitrogen, they appear yellow.

Rough diamonds were first discovered in India almost 2,500 years ago and many ancient civilisations have been captivated by their appearance and touchable texture. Diamonds were a symbol of power long before they became a symbol of love, and were often worn by Kings and Princes going into battle as talismans.

Rough diamonds
Rough diamonds

4Cs – What’s it all about?

Please see this informative short video. It’s produced by the G.I.A laboratory, regarded as the foremost worldwide grading centre.

G.I.A do not value, buy, or sell stones, they only grade for certification purposes, and it’s a blind process as the video will show.

Grading is only a tiny part of the G.I.A expertise which in fact covers an amazing array of skill-sets on their campuses invaluable to the gem industry as a whole and the science behind it, along with research and development.

For clarity we are neither bound to use G.I.A or have any affiliation with them, we are a free agent to supply you with whatever gems we feel are suitable, using our own expertise, to help with your enquiry.

Loupe Fine Jewellery

Diamond Shapes

Polished diamonds are finished in many different shapes, even special-order shapes such as horse heads, or a Christmas tree!

Here are images for a dozen images of the most popular shapes used today. Each shape has pros and cons so we will always help you decide dependant on what item you are trying to achieve.

Diamond shapes

Our top 5 tips for buying diamonds…



Never buy a stone blind from just reading the certificate. Expecting the stone to look as good as it reads is a huge mistake. You do not have the expertise to do so. We rarely do this as professionals why would you?

These two stones shown are virtually identical on the certification, yet are very different when viewed. The left-hand stone is lifeless.



Buy by comparison, looking at one stone in isolation is an error, even if it appears to be nice at the time. Comparing similar stones together can throw up all manner of issues, you will be pleased you compared.

Here is one example of three Pear shapes of the same carat weight but polished to different ratios, without comparisons how would you know which shape you prefer?



Think about the look you want to achieve, is it more fun to have size over top quality? One example are ear studs, using lower grade stones than one may use with an engagement ring often still has the desired effect. So, a discussion on this subject will get the jeweller thinking on the right lines from the outset.



Diamonds do chip & break, it’s very common. Once polished from its natural ‘out of the ground rough’ status, they have quite fragile girdles (Edges). Try to have them checked once a year, if you have chipped the stone edge, and knock it again in the same area it can easily fracture beyond repair, while a minor chip we have options; including re-polishing the chips away.



Don’t be tempted to buy diamonds under poor lighting, or yellow tint lighting, even a dull cloudy day can make them all look the same. Try to have lovely clear daylight, or a professional jeweller’s lamp as it’s a constant source.

The London Diamond Bourse

The London Diamond Bourse, circa 1940

The London Diamond Bourse first opened its doors in 1940. The necessity for London to open a trading floor came about mainly as a result of the occupation of Belgium in May 1940 by the Nazis.

At the time Antwerp was the main diamond trading hub of the World, and had for most of its long history been the home of several active trade organisations. Amongst the refugees who managed to reach this country were a number of diamond merchants. In some cases, they were able to bring their own stock with them. The fables go that the refugees managed to get their stock out by sewing the diamonds into the lining of their garments in order to smuggle their stock across the borders.

The London Diamond Bourse was not a lavish building in the heart of the City of London, in fact it’s first location was in Greville Street inside Mrs Cohen’s Cafe, near its junction with Hatton Garden. A Committee and President were elected and, notwithstanding the very cramped and primitive conditions, the organisation worked with remarkable success.

From 1945 onwards, there was an influx of members, some of whom were survivors of the Nazi occupation and concentration camps. As many of these had lost all their possessions and, in the cases of younger ones, missed their education, they started as diamond brokers with the help of those already established as merchant. By mid 1950s, the place was too cramped so the London Diamond Bourse moved to the ground floor of 57 Hatton Garden as a temporary home, a few years later moving into a newly erected building at 32 Hatton Garden, and with Barclays Bank on the ground floor, the London Diamond Bourse occupied the whole of the first floor.

For the first time the London Diamond Bourse had suitable offices, and in the years between 1960-1980 enjoyed prosperous trading. The membership grew to approximately 700. By the end of the 1980s, even these premises proved too small, so when a new large building was planned at 100 Hatton Garden, which would include space for many separate diamond offices, a move was approved.

Rapid changes worldwide within the Diamond Industry and various problems facing the UK Jewellery Trade during the 1980s, the diamond community found its numbers diminishing. London had two established trading organisations, so negotiations with the London Diamond Club were accordingly undertaken, which were to lead to the formation of the new united “London Diamond Bourse and Club”.

Today our membership is increasing. With the boom of social media in recent years, we have embraced this as a positive step towards assisting other facets of our industry. We are attracting members from all sides of the industry. No longer are members purely diamond traders, now we have members who are manufacturers, wholesalers and retailers to mention but a few. We are still the only recognised industry trading floor in the UK.

London Diamond Bourse trading floor
cut diamonds
London Diamond Bourse viewing room

The London Diamond Bourse (a member of the World Federation of Diamond Bourses) is an exclusive institution, whose history, traditions and facilities make it unique in the UK.

Our members subscribe and are bound by our historic code of conduct which includes integrity, moral obligation, the highest standards of trade and best business practice. The London Diamond Bourse is recognised by the Foreign and Commonwealth office as a Trade Organisation and as such all our members are required to adhere to the Kimberley Process and provide annual certification to validate any trade in rough diamonds.

Being a member of our organisation provides your customers with assurance that they are trading with an individual who has pledged to uphold the traditions, principals of mutual trust and consideration within our industry.
Buying a stone or jewellery from a member of the London Diamond Bourse assures that the goods purchased are from a vetted professional of good standing who is accountable to the industry for their business dealings.

The London Diamond Bourse is the only Diamond Trading floor of its type in the country. Membership to our organisation is earned not automatically granted. As an organisation, our fees are derived from our controlled expenses and our Board members are volunteers from our membership, who do not receive payment or expenses for their work. We employ only the staff necessary to facilitate our business.

Our sole purpose is to provide regulation and support to the UK diamond industry as well as inspire consumer confidence in the trade.

Sign up to our mailing list

We occasionally send our customers offers of pre-owned jewellery and watches, if you’re interested sign up here