Which gemstones have resale value?
Demand is usually strongest for fine diamonds, rubies, sapphires and emeralds. Other natural stones, including moldavites, aquamarines, tourmalines and quality garnets, can also have value. The name alone is not enough: authenticity, quality, size, treatments, origin and demand determine whether a particular stone is marketable.
| Stone | Main valuation factors |
|---|---|
| Diamond | 4Cs, certificate, fluorescence and treatments |
| Ruby | colour, transparency, origin and heat or other treatments |
| Sapphire | hue, saturation, clarity, cut, origin and treatments |
| Emerald | colour, clarity, fractures and the extent of oiling |
| Moldavite | authenticity, locality, size, shape, surface and damage |
Authenticity comes first
The market includes synthetic stones, imitations and natural stones treated to improve appearance. Visual inspection alone may not distinguish a synthetic sapphire, glass imitation or treated natural gem. We use magnification and gemmological instruments; significant stones may benefit from a recognised laboratory report.
Colour, clarity, cut and carat weight
For coloured gemstones, hue, saturation and evenness are especially important. Clarity standards differ by mineral: inclusions are more typical in emeralds than diamonds. A good cut supports colour and brilliance without unnecessary weight loss. Carat measures weight, but a heavier stone is not automatically more valuable per carat.
Natural, synthetic and treated stones
A synthetic gemstone has the same chemical composition as its natural counterpart but was grown in a laboratory and normally has a much lower market value. Natural stones may be heated, filled or oiled. A disclosed standard treatment does not always remove all value, but it affects the final offer.
Loose or mounted gemstones
A mounted stone can often be assessed initially without removal. The metal, other stones, maker, period and overall workmanship are considered at the same time. Do not remove a stone at home, as this can damage both the setting and the gem.
Gemstone valuation in Prague
At our Prague 1 shop, we assess diamonds and coloured gemstones both loose and mounted. We first confirm that the particular item fits the range we purchase before making a non-binding offer. See diamond and gemstone buying and jewellery buying.
