A Guide to Buying Diamonds and Tanzanite

Everything you need to know about buying engagement rings and gemstone jewellery in Cape Town

A piece of jewellery marks a special milestone and commemorates a cherished occasion with something that’s not only beautiful but also tangible. In short, purchasing a special gemstone creation is an emotionally rewarding investment and a decision that’s not to be taken lightly.

To make sure you’re informed when doing your jewellery shopping, we consulted one of South Africa’s most recognised and noteworthy jewellers, Shimansky, who’re renowned for their expert ability to craft exceptional pieces, about what to look out for when buying diamonds and tanzanite in Cape Town. As professionals who hand-select only the highest quality gems from reputable sources (Shimansky is one of the only jewellers in the country that has a license to source rough diamonds), the folks behind the brand are incredibly clued up about grading stones, and they stress the importance of being in the know prior to making a purchase. By educating yourself, you’ll not only have a better understanding of what it is you’re buying, but you’ll also learn to appreciate all the fascinating intricacies of a single item of jewellery. 

FACTORS TO CONSIDER WHEN BUYING DIAMONDS

In much the same way that there are countless variables that influence the price of a fine wine, there are many factors that contribute to the value of a diamond or tanzanite. The four most important components considered when determining a diamond’s worth are known as the ‘Four Cs’, a universal grading system established in 1939, and together they constitute one of these precious stone’s unique fingerprint. These key Cs are cut, colour, clarity and carat-weight.

Cut

The cut of a diamond is the most important of the Four Cs and the only one that is determined by man. This factor affects how light bounces around within the stone and therefore how sparkly the diamond is. If the shape of the gem is ideally proportional and symmetrical, it retains its ability to reflect the most light and increases in value. However, if the stone is cut too deep or too shallow, light will escape out of the sides and the bottom and shine and value decreases.  The benchmark cut, known as the ‘round brilliant’ or ‘ideal’ cut, is based on the optics of a diamond designer and engineer named Marcel Tolkowsky, who calculated the perfect angle at which a diamond claims “its most vivid fire and its greatest brilliancy”. Today, however, the cut that’s considered the most brilliant in the world is an internationally patented design by South Africa’s own Shimansky called the Brilliant 10.

Colour

This factor refers to the absence or presence of an undesirable yellow or brown tint in white diamonds. The closer the white stone is to being absolutely colourless, the rarer and more valuable it is. This is not to be confused with fancy-coloured diamonds, which are naturally rich yellows, oranges, pinks, greens and blues and are rarer and more expensive than colourless white diamonds.

Clarity

Diamonds may show minute traces of other minerals, which appear as natural imperfections known as inclusions. The factor ‘clarity’ gives an indication of the incidence of these marks, and the clearer a diamond is, or the closer it is to being flawless (no inclusions visible), the more desirable and valuable it is.

Carat-Weight

A carat is a unit of measurement used to indicate the weight of a diamond, with one carat being equal to 200mg. The larger the diamond, the higher its carat-weight and the greater its price and worth. However, the value of a stone is determined by all of the factors above, not just carat size. So, you may, for example, decide to buy a smaller diamond with high clarity and colour or you may opt for a bigger diamond with lower colour and clarity.

*Confidence

This factor is not yet an official ‘C’ but it’s still a widely accepted one. It refers to the amount of confidence you have in the jeweller you’re buying from and the assurance you have that a diamond is as valuable as it is claimed to be. In order to have high confidence, you should make sure that the stone has been certified by an independent diamond body, like the Gemological Institute of America (GIA) or the European Gemological Laboratory (EGL), and that it comes with an authentic certificate, which breaks down the Four Cs. At Shimansky, every diamond is laser inscribed on its girdle with a unique identification number that links the stone to its certificate. This enables buyers to confirm the authenticity and the value of a piece at any time.

Video showing the Four Cs used in diamond grading

FACTORS TO CONSIDER WHEN BUYING TANZANITE

Discovered at the foothills of Mount Kilimanjaro in 1967, tanzanite is 1000 times rarer than a diamond. Its value is also determined in a similar way to the diamond by using the Four Cs.

Cut

If tanzanite is cut too shallow, light will escape from the stone and this will result in a lighter shade of violet or blue and a loss of value. Generally, the deeper the cut, the more intense the hue and the more valuable the stone; the shapes that yield the best colour are the cushion, oval and trillion cuts.

Colour

The colour of this gorgeous gemstone is predominantly blue or violet, and the more intense the hue is, the more rare and pricey the tanzanite is. What sets this gem apart from many others is the fact that it is trichroic; meaning, it has the ability to display three colours, namely violet, blue and red, when viewed from three different directions.

Clarity

The clarity of tanzanite is measured in the same way as a diamond, only using a different strength magnifying loupe. Again, the closer the gem is to being flawless, the more costly and sought-after.

Carat-Weight

The carat-weight of tanzanite is assessed on the same scale as the diamond.

Note: The hardness of tanzanite should also be considered. According to Mohs Scale of Mineral Hardness, this gem is relatively soft and vulnerable to scratches. So, Shimansky does not recommend using tanzanite in engagement rings, which are worn daily and hence easily damaged.

FACTORS TO CONSIDER WHEN CHOOSING PRECIOUS METALS: PLATINUM AND PALLADIUM

Aside from gemstones like diamonds and tanzanite, each piece of jewellery is also made with different metals, many of which are alloys. The fewer additional materials mixed with pure metal, the higher its value.

Gold is a common choice for jewellery. Pure gold is yellow in colour when mined, so to make white gold it is necessary to add other white metals, such as iridium or palladium, to the item. Although this process initially creates a white lustre, the high alloy content means that the ashen sheen will eventually wear off and will need to be re-rhodium plated.

On the other hand, platinum, which is incredibly rare (more so than gold), is a strong metal that’s naturally white when mined, and so its colour will remain white with wear. It is therefore a more durable metal and one that’s far less likely to tarnish or corrode.

Shimansky was the first jeweller in South Africa to introduce platinum into the jewellery market and is therefore fondly known as the ‘Platinum Pioneers’. Since, the brand has also started using palladium, particularly in its men’s wedding bands; though less sought-after than platinum, it is also durable, hypoallergenic and much more affordable.

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Take a piece of Cape Town wherever you go with these souvenirs.

Looking for a place to buy diamonds and tanzanite in Cape Town? Read about the jewellery showroom at the V&A Waterfront here.

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