Study of Interdependence: Fancy-color Diamond Appearance, Cut, and Lighting Conditions
2. The DiamCalc modeling technology
The modeling technology was verified by comparison of actual photos under a ring shaped light source and Diam Calc 3D models of a yellow round brilliant CZ (Figure 4):
|Figure 4. A colored round brillian cut CZ with proportions close to Tolkowsky is photographed and modeled (botom row) under a ring-shaped, daylight-equivalent lamp.|
The DiamCalc software can closely model the appearance of polished colored stones in any lighting condition, thus it is possible to model the appearance of any colored CZ or diamond in various cuts as represented in figure 5.
|Ring 6 cm||Ring 17 cm||Office||Jewelry store (white background)|
|Figure 5. Five cuts (round, princess, radiant, oval, and triangle) are modeled in DiamCalc software under various illumination conditions. The round, princess, and radiant cuts are scanned models with real symmetry deviations. The oval and the triangle cuts are parametrical models. Each row contains images of the same stone model in different lighting conditions. The ring lightings are symmetrical illuminations, while the office and jewelry store environments are "real situation" illuminations; these stones are modeled face-up.|
There are shapes and proportion sets that have better look in one illumination but worse on another. But other shapes are more stable to lighting changes:
|Figure 6. A radiant cut apearance is more stable while an oval is better in the Dialite light (bottom row) and a round is better in the Office light (top row). The background is modeled|
3. Colored diamond models under various illuminating conditions
Even though these results were obtained with CZ material, diamond appearance can be modeled with this software (see Figures 7 and 8) by using the appropriate refractive index and the absorbtion spectrum.
It is advisable to use several controlled lighting conditions when designing and optimizing new cuts because of diamond's variability in appearance under different lighting conditions. Diamond proportions that have an inconsistent appearance under different types of lighting can be avoided. A good diamond cut should have an attractive appearance under all lighting conditions. One can use computer models of several common illuminations to predict stones appearance before stones are cut.
|Ring 6 cm||Ring 17 cm||Office||Jewelry store|
Figure 7. Colored diamond models under various illuminating conditions. Stones size 7 mm.
4. Colored diamond models based on another type of absorbtion spectum
Data of spectrums are used in the poster:
- Yellow CZ absorbtion spectrum is used for Figures 1-6.
- Yellow diamond absorbtion spectrum is used for Figures 7.
- Yellow diamond absorbtion spectrum is used for Figures 8.