The word CARAT is derived from the ancient words ‘Keration’ (Greek) and ‘Qirrat’ (Arabic), both of which were names given to the seeds of the Locust or Carob Tree.  Due to their relatively consistent size and weight, dried Carob seeds were once widely used by merchants as counterweights for weighing gold, diamonds, gemstones and pearls.

In 1913, after many attempts to standardise the weight of the Carat, the United States, United Kingdom and Europe adopted the use of the Metric Carat, which has become the standard unit of weight used throughout the diamond and gemstone industry today: 1 Carat = 0.2 Grams.

The Carat is further divided into Points, a unit of weight used only for diamonds: 1 Point = 0.01 Carat.

The size of a finished polished diamond is directly related to its Carat weight.  However, the actual dimensions are entirely dependent upon its proportions.

On average, a well proportioned 1 Carat round brilliant cut diamond has a diameter of approximately 6.5mm.  In comparison, a shallow cut diamond of the same weight may be anything up to 20% larger in diameter, whereas a deep cut diamond of the same weight may be as much as 20% smaller in diameter.

Princess cut diamonds are an increasingly popular choice for engagement rings. 

The princess cut diamond was designed as a square version of the round brilliant cut.  Combining superior sparkle with maximum weight retention, this cut truly does reign supreme.

Also known as a square modified brilliant, the goal of the princess cut was to achieve the weight retention of emerald cuts and the superior scintillation and brilliance of the round brilliant cut.

Weight retention can be as high as 70 to 80 percent of the rough diamond.  In comparison, a well-cut round brilliant is typically around 45 to 50 percent yield of the same type of rough diamond crystal.  This means a piece of rough that would cut two 80-point round diamonds would typically yield two 1-carat princess cut diamonds.  Consequently, a 1-carat princess cut sells for a price closer to that of an 80-point round brilliant cut diamond.

The scintillation of the princess cut comes from the interaction of the crown facets over the top of the pavilion facets which create smaller “virtual facets” than other square-shaped cuts and even smaller and more frequent sparkles than a round brilliant diamond.  There is more internal bouncing around of the light inside a princess cut, which also has more frequent pin fire as opposed to less frequent broad flash fire of a round brilliant.

The origin of the princess cut dates back to 1961 when A Nagy of London developed the profile cut.  It had multiple faceting on the pavilion, but was much flatter than the modern princess and did not exhibit the same sparkle.

The round brilliant cut is by far the most popular diamond cut in the jewellery market and for engagement rings in particular.  It accounts for approximately 75 percent of diamonds sold today.

Owing to its symmetrical shape, this diamond cut is known to be the most optically spectacular of all cuts, reputed for its superior sparkle.

The modern round brilliant diamond is comprised of 58 facets - eight star, eight kite and 16 upper-girdle facets on the crown with eight pavilion and 16 lower girdle facets, as well as an optional cutlet.

The brilliant cut was not invented by one person, but developed over time and the prototype can be found at the beginning of the 15th century.  Indeed the term “brilliant cut” did not come into general use for some time - it was first mentioned in a jeweller’s inventory in 1614.  Improvement of diamond-cutting technology in the early 19th century allowed jewellers to tweak the cut to resemble the round brilliant cut known today.

An interesting bi-product of the round brilliant that has become a selling tool in recent years is the hearts and arrows pattern that sometimes appears when the stone has been cut correctly.  Viewed from above, and only visible with a special viewer, one can see a number of arrows that result from the symmetrical positioning of facets.  Viewed from beneath, the pattern manifests in small heart shapes. 

However, the presence of the hearts and arrows pattern does not guarantee that a diamond will be the most brilliant.  In fact, not all ideal round brilliant diamonds even have this pattern.

In recent years major diamond grading laboratories such as GIA and HRD have conducted much research on the ideal diamond cut proportions.  They all agree there is no one set of proportions that is the “best”. 

Fluorescence is the visible emission of light which occurs when a diamond is exposed to ultraviolet light. It is a natural characteristic, observed in nearly one-third of all gem-grade diamonds, resulting from the presence of trace amounts of Nitrogen, a common impurity in diamonds.

The most common fluorescence colour observed in diamonds is blue, although other colours are possible, such as yellow, white, green and very rarely orange and red. In diamond certificates, fluorescence is usually classified as None, Faint, Medium, Strong or Very Strong.

Many people are falsely led to believe that fluorescence is a negative quality, when in fact it can have either a positive or a negative effect on the colour and overall look of diamonds. Diamonds with high colour gradings of D, E and F, exhibiting medium to strong fluorescence, can often look somewhat hazy or ‘oily’ in direct sunlight. However, those with relatively low colour gradings, around I or J, usually appear one or two grades better in colour due to the masking effect of blue fluorescence.

The effect of fluorescence on the value of a diamond depends entirely upon its strength and colour. The stronger the fluorescence the greater the negative effect can be on the value of higher colour grades and conversely, the greater the positive effect on the value of lower colour grades. The value of higher colour grades can be discounted by as much as 5% to 10% and the value of lower colour grades can be increased by a similar amount. Weak or faint fluorescence tends to have little or no effect on value.

As the name suggests, the emerald cut was originally popular for cutting emeralds. The emerald cut is typically rectangular, although it also comes as a square, called the square emerald cut. The Asscher cut, patented during the Art Deco period, is one version of this.

Reputed for its understated, sophisticated look, the emerald cut has less flash - reflection and refraction - than brilliant cuts; however, the larger facets are renowned for showing large, strong flashes of fire. The light return of these stones is less important than the effectiveness of the patterns and scintillation.

Because it is flat-sided, this cut lends itself to easy pairing with a range of side stone shapes. The quality of the diamond must be fairly high, as less faceting means inclusions are much easier to see - SI stones are often not eye clean. Colour also shows up rather too well, so it is advisable to look sideways, lengthways and diagonally when colour grading an emerald cut diamond.

A good length-to-width ratio is also important when selecting quality emerald cuts. While leading labs say a length should be between 1.5 and 1.75 times the width, lower ratios are also quite popular.

While blue is the most common colour of sapphires, it is found in everything from deep indigo to subtle violet, as well as pink, orange, green, brown and grey. Such derivations from the norm are called fancy sapphires; however a vivid, cornflower blue, verging on violet is considered the gem’s most valuable shade. Indeed a sapphire too dark or light in colour has a much lower value than one with more vivid tones.

Sapphire is a form of the mineral corundum - a colourless mineral formed from crystallised aluminium oxide. In fact, corundum in all colours belongs to the sapphire family except for red, which is called ruby.

Today, sapphires are mainly sourced from Thailand, Sri Lanka, Australia - the source of yellow and green varieties - Madagascar and Tanzania. Most of the fine blue sapphires on today’s market are from Sri Lanka and Madagascar. Kashmir, Burma,Thailand and Cambodia are also renowned for deep blue sapphires of limited supply.

Cut, colour intensity, consistency and purity are the deciding factors in a sapphire’s value. The finest sapphire should not contain any secondary colours or nuances because this will diminish its value and beauty.

Despite being a hard gem, rating nine on Moh’s scale, sapphire must still be treated with care. The gem is slightly brittle and can develop internal flaws and cracks if dropped on a hard surface or delivered a sharp blow.

Sapphire is the birthstone of September and the gemstone for the 5th and 45th wedding anniversaries. For its striking beauty and versatility, sapphire-set jewellery remains ever-popular.

At 95% pure, platinum is the purest of all the precious metals - this is why it is sometimes referred to as 950 platinum. This purity level provides a fantastic shiny finish to a platinum engagement ring, perfect for maximising the brilliance of the diamond itself. Because it is generally 95% pure (18 carat gold is 75% pure), platinum jewellery does not fade or tarnish and keeps its looks for a lifetime. Platinum’s purity also makes it hypoallergenic and ideal for those with sensitive skin.

The most appealing characteristic of platinum is its durability. Each time other metals are scratched or polished, a tiny bit of metal is lost. But not with platinum. Whilst platinum does scratch, the mark on an item of platinum diamond jewellery is merely a displacement of the metal and none of its volume is lost.

Platinum is also very rare - about 30 times rarer than gold. As a result, you do pay a premium for this metal.

Handmade diamond engagement rings are our speciality. At Larsen Jewellery you’ll choose your diamond from a selection of loose diamonds and deal directly with the jeweller who will handcraft your ring. Importantly, when buying directly from our jewellery workshop, you avoid the high retail mark-ups.

With the help of one of our jewellers you can design your own engagement ring to create something truly unique or, alternatively, you can use our many engagement rings on display to help you choose a design.

Click here to view a selection of engagement ring designs, including brilliant and princess cut engagement rings.