The special play of colors of colorless gemstones with high dispersion is called fire , which is emphasized by special cuts and is considered a quality feature. The fire is best known for diamonds .
In the case of gemstones with high dispersion, white light is refracted and broken down into its spectral colors . Only colorless or slightly tinted stones show particularly clear dispersion. Colored gemstones, on the other hand, obscure the dispersion effect. Facet cuts can intensify the dispersion and thus the fire.
The fire is measured via the refractive index and the dispersion . Fire manifests itself in many thousands of colored points of light that change in many ways when turned.
As a starting material, the diamond typically has particularly high refractive and dispersion values, which - in addition to its hardness - distinguish it as a gemstone. Other gemstones with high dispersion include rutile , sphalerite , titanite , zircon and the synthetically produced zirconia .
In addition to brilliance, fire is an important quality feature of a pure stone and a precise cut. The zirconia have a little less brilliance, but more fire than the diamonds. The setting also contributes to the fire of the stone because it gives it additional color nuances. Therefore, an interplay of setting and stone is important for all transparent stones for this reason.
The iridescent sheen of jewelry pearls and related materials, on the other hand, is called luster or pearlescent .
- Walter Schumann: Precious stones and gemstones. All kinds and varieties. 1900 unique pieces . 16th revised edition. BLV Verlag, Munich 2014, ISBN 978-3-8354-1171-5 , pp. 41 .
- ^ Walter Schumann: Precious stones and gemstones. All kinds and varieties. 1900 unique pieces . 16th revised edition. BLV Verlag, Munich 2014, ISBN 978-3-8354-1171-5 , pp. 54 .