A Guide to Buying Diamonds and Tanzanite

Everything you need to know about buying designer jewellery in Cape Town

A piece of jewellery represents a special milestone and commemorates an occasion that’s meant to be unforgettable with something not only beautiful, but tangible. In short, buying a piece of expensive jewellery is a lifelong investment, and is a decision not to be taken lightly.

Thus we consulted the experts, Shimansky jewellers, to find out the ABCs, or rather, the 4Cs, to buying diamonds and tanzanite in Cape Town. As the professionals, they highlight the importance of becoming more in the know prior to putting your shopping face on – by educating yourself you’ll not only have a better idea of what you are buying, but you’ll also learn to appreciate the fascinating intricacies behind a single piece of jewellery.

What to look out for when buying diamonds

The truth is, one carat does not equal one fixed price. There are many factors that contribute to the value of a diamond or a piece of tanzanite, in much the same way that there are countless variables that influence the price of a fine wine.

The four Cs, established in 1939 by the diamond board, are the four most important components considered when determining diamond price, and together, they form a single diamond’s unique fingerprint.

Cut
The cut of the diamond is the most important of the four Cs. The benchmark-cut, or the cut that all diamond cutters aspire to, is based on the optics of a diamond designer named Marcel Tolkowsky. This Belgian engineer calculated the ideal angle at which a diamond claims ‘its most vivid fire and its greatest brilliancy’, meaning that perfect cut at which the diamond retains its ability to reflect the most light. If it’s cut too deep or shallow then light escapes out the sides or the bottom, leading to a loss of brilliance. If the shape and facets - the flat faces of the shapes - are also symmetrical this significantly increases value.

Colour
Colour refers to the absence or presence of a yellow tint in diamonds. The closer the diamond is to being colourless, the more valuable it is.

Clarity
Diamonds may show minute traces of other minerals, which appear as marks / inclusions. The closer the diamond is to flawless, the more valuable the diamond.

Carat
The weight of one carat is equal to the weight of one carob seed, and has been measured accordingly for centuries. However, value is determined by all of the above. You may, for example, decide to buy a smaller diamond with high clarity and colour; or, you may opt for a bigger diamond, with less clarity and colour.

Make sure that your diamonds are certified by independent diamond laboratories, like the Gemmological Institute of America (GIA) and the European Gemmological Laboratory (EGL), and be sure that you are provided with an authentic certificate, which breaks down the four Cs.

At Shimansky, the diamonds are laser inscribed with a unique diamond identification number in letters no larger than a few micron on the diamond’s girdle. This identification matches the diamond with the certificate, which enables buyers to confirm the authenticity and the value of a piece at any time.

What to look out for when buying tanzanite

Discovered in the foothills of Mount Kilimanjaro in 1967 by Mavel de Souza, tanzanite is one thousand times more rare than the diamond.

Colour
The colour of tanzanite is predominantly blue or violet. The more intense the colour of Tanzanite, the more rare and valuable it is. What sets Tanzanite apart from any other gem stone is that fact that it is trichroic. This means that Tanzanite has the ability to display three colours at once namely violet, blue and red.

Cut
If tanzanite is cut too shallow, light will escape from the stone and this will cause the colour to die easily. Thus, it will lose value.

Clarity
Measured in the same way as the diamond.

Hardness
According to the Moh Scale (which measures gemstone hardness), tanzanite is relatively soft, so Shimansky does not recommend this for an engagement ring.

Platinum: as durable as the strongest long-term relationships

Aside from the semi-precious stones (diamonds and tanzanite), each piece of jewellery consists of pure metal and added alloys. The fewer alloys added to the pure metal, the higher the carat and value of the metal.

For example, pure gold is yellow in colour when mined. To make white gold, it is necessary to add white metal alloys, such as iridium, palladium and rhodium to plate the item. Although the process initially creates a white lustre, this will eventually wear off due to its high alloy content and will need to be re-touched.

On the other hand, platinum, which is incredibly rare (30 times moreso than gold), is a white metal that’s known for its durability; it’s far less likely to tarnish or corrode. Platinum, which is naturally white when mined, requires only the minimum amount of added alloys (only 5% added alloys, compared to 18-karat gold’s 25%), which enables it to be stronger and easier to maintain. Shimansky were the first to manufacture platinum jewellery in South Africa, and are fondly known as the Platinum Pioneers.

To find out more about diamonds, consider taking a tour in the Cape Town Diamond Museum.

By Lisa Nevitt

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