valuing diamond jewellery

Valuing Diamonds – What Determines Their Worth?

A diamond’s value depends on many factors and, as London pawnbrokers since 1770, the Suttons and Robertsons’ diamond specialists know exactly what they’re looking to see in a gemstone. We can offer you a loan against your jewellery collection and have over 250 years of experience, if you are seeking to pawn a diamond ring, necklace or earrings. We’ll be pleased to take a look at your item, either in-store or online, and offer you a free valuation on your piece.

Diamonds are the cornerstone of jewellery design and they hold their value, but where they are, how they’ve been set, the size and carat and the brand are all important factors in a valuation. A Cartier diamond pave ring may dazzle and shine but how will it compare to the value of a Graff diamond solitaire engagement ring? It depends on the carat, clarity, cut and colour of the diamond as well as the size. Together, these are known as the 4 Cs and they were created by the Gemological Institute of America to act as a benchmark for deciding diamonds’ worth.

valuing diamond jewellery

What exactly is a Carat?

A diamond’s carats refer to the weight of a diamond. One carat represents 0.200 grams in weight. What this means when valuing a diamond is that the larger and heavier it is, the greater its value. One single stone will always be valued at a higher price than two smaller stones combined. This is because larger diamonds are rarer and, as such, attract a higher valuation. A large solitaire diamond ring could be valued higher than an eternity ring with the same carat value as one large diamond has greater value than many small ones that add up to the same carat.

Large diamonds are also valued more highly because of the effect that a large diamond has over and above smaller stones of the same quality.

Diamond Clarity

A diamond’s clarity refers to its purity and takes into account the number and positioning of inclusions (internal flaws) and blemishes (external marks). The fewer the number of inclusions and blemishes, the higher the diamond’s value. Diamonds are magnified by 10 times to assess their clarity. Five key factors are examined. These are the position, size, nature, colour and the number of inclusions and blemishes. It is often only at this great magnification that flaws can be seen; some are invisible to the naked eye.

Gemstone Cut

The value of the other Cs rest in what nature provides, but it is the brilliance of the craftsman who works on the diamond that gives it its cut value. A diamond’s cut is what lets light reflect through the diamond and it is a cut that can truly realise a diamond’s true beauty.

When cutting a diamond, there are three optical effects that can be created:

  • The Brightness – white light reflection, both inside and out.
  • The Fire – How white light is transformed into the colours of the rainbow
  • Scintillation – The reflections, or sparkle, caused by the pattern of light and dark within the stone


Colour can have a massive impact on the value of a diamond. A large flawless white diamond could be worth less than an ultra-rare smaller yellow diamond with a few blemishes or inclusions. Most famously white or colourless, diamonds also come in colours such as grey, pink and blue, but the less colour a ‘white’ diamond has, the greater its worth. This is because the lack of colour generates more sparkle, and identical seeming diamonds can be valued differently on the basis of their colour.

While white diamonds are graded on a chart from D to Z, where D is completely colour-free and Z has colour evident; however coloured diamonds are rated on a different scale which rates a stone according to its strength of colour.

The Beauty of Brand Value

A fabulously-cut high quality diamond might generate a generous valuation but it might be worth even more if the diamond is nestled in a setting made famous by the world’s great jewellery houses. A Cartier LOVE bracelet may have lots of small diamonds while a Tiffany diamond pendant could be set with a large stone but the valuation will depend on the condition, the provenance and on the availability of the certification documents. It’s also important to remember that a brand piece will always have a greater value when bought from the brand store directly, rather than a resale price.

That’s a Rap

As trusted London pawnbrokers, we rely on a point of reference for our valuations. We know that our clients may be in urgent need of a short-term fast loan and so we turn to the Rapaport Research Report for a cost on every diamond that we see. Called the ‘Rap Price’, the report states the base price industry-wide for diamonds. Not only does it take the guesswork out of the equation, but it lets you – the customer – know that our valuation is reliable and based on a recognised valuation framework. The report will help us to arrive at a price according to cut, colour, clarity and carat as well as identify what your diamond is.

Looking to Release the Value in Your Diamond Jewellery?

As a London pawnbrokers, we never know what to expect – and we’ve had some wonderful surprises over the years. We’ve also had some disappointed clients who thought that their stone may be held more value than it did. Simply put, diamonds don’t lie.

Backed up by the Rap Price, we’ll be able to make you an expert diamond jewellery loan valuation or diamond jewellery purchase offer. Our valuations are fast, meaning that you could get £500 – £20k almost instantly.

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