Guide to Buying a Diamond Ring

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Before you venture forth and buy your beloved a diamond engagement ring, read my mini-masterclass here.

If I had a pound for every time I’ve been asked “how much does a diamond cost?” well, I’d have a tall stack of pounds. It’s frustrating to not be able to answer this question clearly.  However, it’s a bit like asking someone, how much does a home cost?  Like anything, it’s to do with size, quality, and availability and personal taste.  Very roughly, as a rule of thumb, a round brilliant cut diamond that is 3/4 carat (ct) is about £5,000 plus the mount, yet one marginally bigger at 1 ct in weight and of the same good commercial quality will currently cost around £11-12,000 plus the mount.  Amazing how much size does matter! You can spend much less or much more depending on what carat weight, and category of colour, clarity or cut the diamond is. (prices as per Jan 2019)

A bit of knowledge on the subject helps here, because understanding how diamonds are categorised and therefore valued, will help inform your purchase; but let’s forget spending 3 months’ of your salary on an engagement ring.  I think this formula was spun by De Beers when they created the American market after World War II, and it needs to be dumped. Just have a realistic and comfortable sum and never feel you should spend more if you can’t. That way you will enjoy investing for the long term.

Just dwell on this amazing thought before we dive in -  each diamond you gaze at was formed about 1 - 3.5 billion years ago from molecules of carbon trapped about 150 km under the earth’s surface, at 1200 degrees Celsius, at a pressure of 5 thousand times greater than our normal atmosphere (that’s the equivalent of the whole of the Empire State building, compressed on top your foot) and then was blasted to the surface of the earth in a cataclysmic volcanic eruption.  The very existence of diamonds at all is a serious freak of nature!

Anyway, let’s return to the point and some technical knowledge!   You may have heard about the 4 Cs, the quality/cost factors of diamonds, these are:

The 4 Cs: Carat, Colour, Clarity and Cut

Carat – the unit of weight for all precious stones is a carat. One carat (ct) is 200mg – the average weight of a raindrop.  Vast quantities of rock are moved for each diamond found, often 100 tonnes per 5cts of rough found, that’s 7 solid double decker bus amounts of rock for a tiny amount of crystallised carbon.  In any case,  most are industrial quality – only 1 in 3 diamonds found is used in jewellery, and only 1 in 6 is a gem good enough for fine jewellery; the rest is used in industry for cutting tools.  Considering that the average rough diamond weighs less than 1.10ct when it’s mined, and it will lose over half its weight in cutting, consequently only a minute amount of stones, 0.01% of rough diamonds will yield a finished stone larger than 1ct  - you can now see why diamonds are so expensive the bigger they get.

Colour – most diamonds are yellowy-browny, due to varying amounts of nitrogen within the carbon crystal when it formed, so finding diamonds without this tint is hard!   In diamond terms colour is measured on an alphabetical scale starting at D not A (note the idiosyncrasy). Grade D is completely colourless, and the scale runs through from D to Z; a diamond is clearly tinted to the untrained eye at about K.  Fancy vivid colours like pink, blue and orange are a realm of rarity altogether.

Back to the 4 C’s and we are at C for Clarity.  This refers to the presence and number or type of tiny natural features called ‘inclusions’ inside the stone which can be found with examination under 10x magnification, and from what you know now about the birth of diamonds, it’s really not surprising there are any. When the naked or untrained eye can see something that detracts from the stone’s beauty or ability to sparkle this is a serious issue and at the other end of the scale, a diamond that is perfectly free of any inclusions is almost unbelievably rare and expensive.  Most diamonds have something an expert will spot.  If you are hung up over clarity or colour, invest in colour as this is more easy to judge for non-experts. 

Cut – the shape of the stone, and the expertise and quality of its symmetry and polish.  Given that by far the most popular cut and shape is the round brilliant cut, this is also the most highly prized.  There are 57 facets cut onto a brilliant cut, which should all be perfectly angled to release maximum sparkle and brilliance – what we call fire.  Oval and cushion shape diamonds used to be considerably cheaper but now are so fashionable, they have gained in price!  Princess-cuts, first designed in the 1960’s combine a square outline with the brilliant cuts’ multi-facets. If you are a purist and prefer your ice cool, then baguette, octagonal, or Asscher cut diamonds are quieter and more lustrous than their sizzling sparkling sisters, and are also less expensive per carat.  However, whatever the shape, if a stone is poorly cut with mismatched angles and facet edges, or polished badly, the sparkle isn’t so well defined, and this detracts from the diamond’s innate beauty. 

The 4 Cs are really the 4 Considerations.  Which are the most important to you, what would you compromise on?  Get the best quality you can for your budget, that way you know you will be buying well for the long term.

Most jewellers will have a diamond that weighs over 0.30 ct examined and graded by specialists in a recognised laboratory, so you will have a Diamond Grading Report Certificate to look at and discuss when you are considering what diamond to buy.  You’ll be given this report when you make your purchase.  Keep it safe as they cost a fortune and can’t be duplicated.   The most popular lab reports are from the GIA (Gemological Institute of America) however other labs are available!  In any case, all reliable sources will be committed to the best ethical practices and your invoice should state that the diamonds supplied were handled in accordance with the Kimberley Process Certification Scheme (KPCS) which ensures that they originated from countries or mines not involved in conflict. 

Diamond Ring Design

So much for the bling – now, how about the design? Obviously any ring set with any gemstone, even diamonds which are famously the hardest material in nature, is a fragile miniature construction of precious metal, and must be treated with care and respect if you want it to last a lifetime!  I advise you buy a good sturdy setting, one that that is practical and won’t snag or catch in careful daily wear.  Buying antique? Get it re-made and don’t chance it. Settings and claws on antique rings are not secure. An engagement ring will last one careful lady owner just one lifetime, not more. 

For a ring that will last a lifetime buy quality - the higher the precious metal content, the better – when we say ‘18ct gold’ it means 18  parts pure of gold out of 24 parts where the other metals in the alloy mix would be copper or silver or both. White metals used in jewellery are platinum and white gold; sometimes you may find some designers using another platinum family metal called palladium, which is a pure white colour, less expensive than gold and platinum, and can be hallmarked.

Platinum – a very rare, expensive, dense, precious pure white metal, which is resistant to tarnish and takes a great polish. In standard hallmarkable items, 950 parts are pure platinum mixed with 50 parts of a tiny amount of other metals just to soften it.

Gold – loved by humans for millennia, this tarnish free and warmly lustrous precious metal is irresistible. Gold is a naturally a soft malleable material hence the addition of other materials so it can take a good bright polish and hold its form. It is available in different carat purities according to the ratio of pure gold to other metals alloyed with it such as silver and or copper. 18ct white gold is 18 parts per 24 of gold, plus silver or palladium, and because it’s mostly yellow gold, is never pure white so it is often plated with rhodium (a platinum family metal) to get a truly white metal surface. Rose Gold has some extra copper instead of silver to make the gorgeous pinky colour, which looks amazing on dark skins or redheads.

You could always have a combination of coloured and white metals, a white collet shows off a white diamond beautifully, and the golden band looks fantastic with a classic yellow gold wedding ring. Very regal.

Now you’re almost done, but let’s consider the wedding ring, as it will be worn together with the engagement ring, and may even match yours if you are going to have one, too. Some ladies like the feel of their rings to sit flush and snug like stacking rings, and others don’t mind the gap…  Neither way is right or wrong.  It’s all a matter of individuality!

Get in touch for more help and a no obligation hands-on mini-masterclass. Email: Tel: +44 7879 413091