Buying of loose gemstones
The price of a gemstone is mainly determinated by its colour, cut, clarity and weight.
In the international diamond-market the 4 Cs (carat, colour, clarity and cut) are relevant for the price – they can also be used in a similar way when buying coloured gemstones.
The price of gemstones is calculated by their weight (1 carat is 0,2 gram). As large gemstones are usually rare, their price per carat is considerably higher. This effects especially the so called "precious gemstones", like ruby, sapphire and emerald – also some more high-quality gems like tanzanite, mandarin-garnet, tsavorite and others.
The colour is a very important factor for price-building of gemstones. The more vivid and saturated the colour is, the higher the price of a gemstone rises.
Gemstones without eye-visible inclusions are absolutely top-valued. Coloured gemstones mostly have tiny inclusions – just visible by using a loupe. Absolutely flawless gems are rather rare and most valuable. Small inclusions, which do not effect the brilliance of the gemstone, make the stone cheaper but do not matter its beauty.
The cut and especially the faceting of a gemstone increases its value because of showing brilliance, flashes and sparkles. Well cut gemstones always look lively - refracting and reflecting the light by selective absorption.
Some natural gemstones occur very common, others are quite rare. This is also an important factor for the price.