It may not look like an incredible object in its natural form, but once a stone has been mined and cut to perfection, it transforms into an object of beauty that is precious and unique.
Gemstones arenʼt just something that you pay a ton of cash for and deliver to your other half in the hopes of obtaining forgiveness for any wrongdoing. They can be a good investment in certain cases. They also bear different qualities that you need to pay attention to when choosing the right stone.
Hereʼs a quick essential know-how, so you wonʼt be confused when you select your next stone.
The standard four ʻCʼs do apply in most gemstones: Cut, clarity, caratage and colour. However, different factors do come into play when different stones are examined.
Diamonds, the most prestigious of gemstones, have a broad colour variation. Coloured diamonds are the result of impurities in the stone, but that does not reduce their value. The presence of boron turns the crystal blue, and nitrogen produces yellow tones. Pink and red diamonds come from structure anomalies as the diamond is formed, while black diamonds are the result of a presence of other forms of carbon than the crystalline structure. Fancy coloured diamonds have a different form of grading based on the rainbow spectrum and intensity, with pure colours ranked higher than mixes.
Colourless diamonds, however, are ranked from ʻ Dʼ to ʻZʼ, across a range that goes from colourless to pale yellow.
Following colour is the clarity that comes into play, which refers to the presence of inclusions or defects in the stone. There are a range of inclusions such as internal knots, other crystals, feathers, pinpoints and bearding. Blemishes can also affect their grading. The Gemological Institute of America (GIA) has a standard scale, with a perfect stone as flawless (FL) down the scale as following: internally flawless (IF), very very slightly included ( VVS), very slightly included ( VS), slightly included (SI) and included (I). Generally speaking, anything above the VS category will be virtually flawless to the naked eye. The International Diamond Council ranks flawless diamonds as ʻ loupe cleanʼ.
Naturally, the less inclusions, the rarer and more valuable the diamond, and the pricier it is per carat.
The traditional precious gemstones are diamonds, emeralds, rubies and sapphires. They are graded in the same manner as diamonds, but when it comes to clarity, they are ranked differently. Inclusions are categorised as solid, liquid, gaseous or optical inclusions, and in the case of emeralds, three-phase inclusions (with a solid, liquid and gaseous inclusion) are highly priced. At the same time, optical inclusions such as trapiche, carbon rays that radiate out from a centre core, are the most prized. Another rare effect in emeralds is chatoyancy or the catʼs eye, formed from fibrous inclusions or cavities in the stone that creates a glowing line within the stone, hence its name. Intensity of colour matters as well in emeralds, and the evenness of colour throughout the stone.
A variation of corundum, sapphires come in several shades and colours, which they are valued for according to the intensity of the hue and the presence of the secondary colour that is present. Like emeralds, inclusions are examined by eye and the most appreciated phenomenon in the gemstone is asterism. Known as star sapphires, this is due to the presence of rutile that forms a six-or-12-ray pattern in light. The catʼs eye effect can also be present. Another rare type is the colour-change sapphire, that offers different shades in light.
Contrary to popular belief, it isnʼt just the precious gems that hold value, though they are appreciated for their rarity. The shortage of precious stones means that semi-precious gems are garnering interest from collectors and brands. Tsavorite, a green garnet that is only found in Tanzania, rarely exists in gem-quality and is measured for its intensity in colour and transparency. It became popular in the last four decades, and yields incredible value today on the market.
Tanzanite is even rarer and found in Tanzania as well, hence its name. It has a unique tri-colour effect that changes from sapphire blue to burgundy depending on the angle at which you view the material. The stone needs to be treated by heat for the tone to reveal itself, and is graded in quality depending on the hue and clarity. Due to the limitations imposed by the government on its mining, it appears at high prices on the jewellery market.