The following pages present some useful information on how sapphires and other coloured gems are graded, valued and described. Similarly to diamond, coloured gems are priced according to the four "C"s. In contrast to diamond, these factors are quite a bit more complex with the added factors of Supply & Demand greatly influencing price. Just to make things more interesting, compared to the tightly controlled diamond marketing cartels, coloured gems are sold at all levels of the supply chain with greatly varying price levels being imposed for gems of comparable quality.
Buying coloured gems can be a complex undertaking, but a basic understanding of the major variables will help consumers make informed buying decisions. We also includes links to information on gemstone enhancement treatments.
When buying a coloured gemstone, colour is paramount. Description of colour is a very complex and individual process which is made more difficult by the differences in how colour is perceived under different lighting conditions. See here for more information on gemstone colour.
CUT and CARAT
Cut refers to the how the shape and finish of the faceted gemstone. Carat is a unit of weight (5 carats = 1 gram) and refers to the size of the gemstone. See here for some notes on how cut and carat weight affect gemstone value.
SUPPLY and DEMAND
In many ways, supply and demand are the most important factors influencing the value of a gemstone. Quite simply, very rare gems will always be valued higher than ones that are more common. Of course, it is not quite that simple as other market factors are also involved. See here for more discussion on supply and demand.
Many gemstones are enhanced by various treatments to improve colour and attractiveness. Some treatments are almost universally done on certains gems and do not affect price - however, in other cases, the use of a treatment may significantly alter the value of the gem. As new treatments are developed which radically alter gems, consumers are increasingly demanding fully natural, untreated gems. See here for more information on the treatment issue and our full disclosure policy.