PEARLS | SAJN jewellery designers. This is due to their remarkable range of sizes, shapes and colours, plus their commercial availability at lower price points. They are usually cultured in freshwater lakes and ponds, often with many pearls grown in one oyster. China is the leading source for freshwater cultured pearls. Just as quality influences diamond price, the same is true for pearls. GIA developed the Seven Pearl Value Factors for the same reasons it developed the Four Cs of diamond quality: to establish a standard terminology for describing pearl quality, using language everyone can understand. And just as the GIA defined the methods and best practices for evaluating diamond quality, it also defined the procedures for evaluating pearls. Like diamond grading, pearl classification is a complex process that takes a trained gemmologist time and extensive knowledge to execute. There are a number of factors that influence their value and how they are assessed.
Pearl value factors Pearls come in a wide variety of sizes, shapes and colours. The GIA Seven Pearl Value Factors is a comprehensive standard it developed over a 60-year period of ground-breaking research on pearls. It provides a systematic way to evaluate pearls of all types and to describe their appearance and quality in a way everyone can understand. The qualities that determine the overall value of a natural or cultured pearl or a piece of pearl jewellery are size, shape, colour, lustre, surface quality, nacre quality and – for jewellery with two or more pearls – matching: 1. Size The size of round and near-round pearls is expressed in terms of their diameter measured in millimetres. Other shapes are measured according to their length/depth and diameter/ width. When other value factors are equal, larger pearls are rarer and more valuable than smaller pearls of the same type. 2. Shape The three main categories of shape are spherical, symmetrical and asymmetrical (semi-baroque and baroque). Pearls come in seven basic shapes: round, near-round, button, drop, oval, semi-baroque and baroque. Round is the most difficult shape to culture, making it the rarest cultured pearl shape and – if all other factors are equal – also generally the most valuable. There are exceptions, though. Well-formed pear, oval, or baroque (irregularly shaped) cultured pearls are also prized by pearl-lovers.
Of the seven pearl value factors, lustre might be the most important. Lustre is what gives a natural or cultured pearl its unique beauty. Different pearl varieties have different standards for lustre. SA JEWELLERY NEWS - MAY 2021
3. Colour Natural and cultured pearls occur in a broad range of hues. There are warm hues like yellow, orange and pink, and cool hues like blue, green and violet. Pearls have a wide range of tone from light to dark. Pearl colours tend to be muted, with a soft, subtle quality. Pearl colour can have three components. Body colour is the pearl’s dominant overall colour, overtone is one or more translucent
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