Introduction
In the jewellery industry, aesthetics is an imperative parameter. These objects are usually composed of several materials that interact with each other and with light, which can affect the visual aspect of each material and thus the perception of the final product. Being able to predict the appearance of a specific element or the final object early in the product development process, without having to rely on a physical sample, is a crucial advantage for product designers.
Gems in particular, with their intricate shapes and optical properties, present difficult challenges for accurate digital simulation. Their complex geometry, coupled with specific surface and volume properties, complicates the dynamics of their light interactions. Achieving highly precise digital representations requires extensive consideration of optical laws and sophisticated computational models.
With Ocean™ Simulation Software, project managers can create a virtual prototype of a specific jewel by generating images and data based on materials measurements and properties. It enables rapid iterations on different parameters and ensures precise control over aesthetic aspects, especially color and surface finish.
Predicting gemstone appearance considering the influence of geometry and light:
Understanding the complex shapes and optical characteristics of gemstones:
The complexity of gem shapes, combined with their sophisticated optical properties, presents significant challenges in digitally simulating them with accuracy. Gems come in a multitude of shapes, ranging from simple geometries to highly irregular forms with numerous facets and curves. Each facet interacts differently with light, causing variations in reflection, refraction, and absorption across the gem’s surface. Moreover, the internal structure of gems, including impurities, inclusions, and structural defects, further complicates their optical behavior.
Figure 1: Due to the complex shape of gemstones, each facet has a different interaction with light.
Achieving accurate digital simulations requires capturing the nuances of these complex shapes and optical properties, which requires careful consideration of the laws of optics as well as sophisticated computational models and algorithms. Factors such as surface roughness, material composition, and light source characteristics must be carefully considered to produce realistic results. In addition, the inherent variability of gemstone properties introduces uncertainty, making it difficult to accurately predict how light will interact with the gem under different conditions.
Figure 2: Illustration of the complex shape of a gem and the sophisticated light interactions. Animation generated with Ocean™
Ocean™ workflow for scientifically accurate gemstones simulation:
The Ocean™ modeling workflow is a systematic approach that integrates several steps to accurately simulate the appearance and behavior of gems in digital environments.
The first step is to analyze the geometry of the gemstone, typically derived from CAD data. This data is imported into Ocean™ and serves as the basis for subsequent simulation and modeling processes.
The next step is a careful analysis of the optical properties of the gemstone. This includes the examination of both volume and surface properties. Volume properties, such as the gem’s dielectric properties (refractive index, absorption coefficients) and scattering characteristics, are carefully examined. Surface properties such as whether the gem is opaque or translucent, its flatness or roughness, and its reflectivity are also evaluated. In addition, emission characteristics and deformation patterns, such as scratches or abrasions, are considered. Each of these properties is essential to accurately capture how light interacts with the gem.
The third stage is the spectral calibration phase. At this point, Ocean™ ensures the physical accuracy of its simulations by comparing the rendered output with real photographs of the gemstone, both captured under identical controlled lighting and environmental conditions. This comparison is based on measured spectral data from the actual material.
By aligning the simulation with real-world optical behavior, Ocean™ enables the identification of colorimetric deviations and ensures visual fidelity. Any discrepancies between the simulated image and the photo are analyzed and quantified using spectral and colorimetric metrics (e.g., ΔE). This allows users to adjust material parameters or optical models if necessary, achieving a simulation that is both visually and scientifically predictive.
Figure 3: Optical validation process for gems simulation
The fourth stage is then the digital observation and iteration within specific scenes, under defined lighting and environmental conditions. This process allows engineers and designers to observe and measure the interactions between light and the gemstone in a controlled virtual environment. This enables several applications, including confirming or refining specific multi-material jewelry designs, evaluating the appearance of gemstones before costly physical samples are produced, and iterating on material compositions to achieve desired aesthetic outcomes.
One of the most valuable benefits of using virtual prototyping is the significant time saved during the iteration phases, as physically setting gemstones is a long process of several weeks or months. With Ocean™, this phase is reduced to hours.
Figure 3: Ocean™ workflow to generate predictive images and lighting quantification for scientifically accurate gemstones simulation.
Examining light’s impact on gemstones appearance:
Light has a profound influence on the appearance of gems. The interaction between light and gem materials involves complex optical processes that significantly impact the gem’s visual properties.
At the core of this interaction lies selective absorption and reflection of light wavelengths by gem materials, dictating their perceived color. For instance, the absorption spectrum of a gemstone like ruby exhibits peaks in the green and blue regions, leading to its characteristic red hue.
In addition, the optical design of gemstone facets plays a key role in enhancing brilliance and dispersion effects. Their different angles affect the propagation of light. Factors such as total internal reflection and light scattering at the facet interfaces must be taken into account, resulting in the overall luminosity and brilliance of the gemstone.
Texture and surface characteristics also contribute significantly to the optical behavior of the gemstone. Surface roughness or flatness affects light reflection and scattering, influencing phenomena such as gloss and transparency. Layered gem structures, such as those found in opals, present fascinating light interference phenomena that lead to their iridescent properties.
The characteristics of the light source itself, as well as the optical properties of the background, must also be considered when simulating the appearance of a gem.
The example below, we illustrate the variations in the aspect of gems depending on the type of light source.
Figure 4: Illustration of the influence of the light source on the appearance of a single gem. Simulations generated with Ocean™
Moving from gem geometry and light we will now discuss the impact of surface treatments and volume properties on the appearance of gems. Through Ocean™, we will explore precise color control and visual effects, optimizing material selection to bring creative visions to life.
Predicting gems appearance considering gemstone surface treatments and volume properties:
Using material measurements, 3D data and following the laws of optics, Ocean™ is able to predict the appearance of a variety of gemstones. It also considers surface treatments and volume properties that have an impact on the appearance of gems. This approach offers a comprehensive and efficient way to enhance material selection and optimize designs.
Two case studies illustrate the versatility of virtual prototyping in gems appearance: multicoated gems and light scattering into gems’ volume. These studies demonstrate precise control over color aspects and the creation of specific coloration effects, while using digital gemstone simulation.
Achieving color precision with Multicoated gemstones:
Optimizing color with PVD Coating and Additional Ink Application:
In view of obtaining specific color aspects, the bottom part of the surface’ gem is PVD coated. An additional ink may be applied on top of the coating.
Figure 5: Applying gemstone surface treatments for aesthetic requirements
Virtual prototyping allows precise control of color aspects by iterating the application of PVD coating or additional ink on various parameters such as composition, thickness, positioning… These techniques allow engineers to achieve the desired aesthetic variations of gemstone surface treatments with precision.
Figure 6: Side View - Various simulations of gemstone surface treatments. Simulations generated with Ocean™.
Figure 6: 35° View - Various simulations of gemstone surface treatments. Simulations generated with Ocean™.
Analysing directional coating effects for aesthetic variations:
Coatings may be used in the jewelry industry to achieve specific light reflection effects. Due to the complex shape of gemstones, which causes a variation in the thickness of the coating on the gemstone surface, it is difficult to anticipate the differences in color that will occur on an entire object.
With Ocean™ it is possible to reproduce a directional monolayer coating on facets with different orientations, making these variations visible and allowing product designers to anticipate color and reflection variations.
Figure 7: Simulation of directional coating on facets with different orientations. Simulations generated with Ocean™.
By experimenting digitally with different coating designs, designers are able to minimize material waste and production costs, as well as reducing the time spent in the prototyping phase. Virtually testing different coating orientations helps determine the most resource-efficient approach while achieving desired aesthetics and offering precise color control.
Exploring gem volume properties: coloration effects via light scattering:
Specific coloration effects can be obtained using integrated nanoparticles into the gem’s volume. Ocean™ is able to predict the appearance resulting in the interaction between the light and those nanoparticules, based on the Mie theory. We explore the phenomenon in a dedicated article “Mie Scattering Coloration”. This approach offers a nuanced understanding of light interaction within gem materials, leading to unique and captivating visual effects.
Light scattering into gems’ volume can result in bichromic behavior, where absorbed and scattered light lead to complementary colors. Virtual prototyping enables exploring these phenomena to create stunning aesthetic effects in gem design.
In the below example, a bichromic behaviour can be observed thanks to metallic nanoparticules with variable size in glass medium.
Figure 8: Simulation of light scattering in the volume, including different sizes of metallic nanospheres, resulting in nuanced coloration effects. From left to right : 40 nm silver spheres, high density of 40 nm silver spheres, 60 nm gold sphere, cranberry glass (mixed of molten glass and gold sphere). Simulations generated with Ocean™.
Predicting gems appearance in a jewelry composition, considering interactions with other complex materials:
In the jewelry industry, gemstones are often combined with other materials to create unique designs. These combinations produce specific interactions that may require a long iteration process to find the best match.
By using Ocean™ during the prototyping phase, designers and product managers can accurately evaluate the best options in a short time by following 3 steps:
- Phase 1 – Material characterization, based on physical samples.
- Phase 2 – Material modeling, from characterizing or available data
- Phase 3 – Appearance simulation for rapid material iteration.
Use case: Ring Appearance assessment with Ocean™ Simulation Software:
In the context of a ring appearance assessment considering various material candidates such as metals and gemstones, Eclat Digital proposes a comprehensive approach that includes material characterization, model building and appearance simulations for each of these materials.
Metal: Challenges and Solutions for predictive simulation:
Metals present challenges in characterization and accurate simulation due to properties such as surface finish, and polarization effects. By combining dielectric function measurements with simulations, virtual prototyping enables iteration with different surface states without the need for new measurements, providing insight into the intrinsic properties of metals and their variations in appearance.
Figure 9: Dielectric function measurement of grey gold and visualization of the result. Simulations generated with Ocean™.
Gems: Predict emerald intensity variation accurately
To find the best composition, emerald and tsavorite gemstones are examined for intensity and color variations based on absorption and diffusion properties. Ocean™ can deal with a large panel of tabulated material data, either theoretical or measured. Introduction to material measurements and fundamental principles of materials simulations are developed in dedicated articles.
Figure 10: Absorption measurements on emerald gemstones. Simulations generated with Ocean™
Virtual prototyping with Ocean™ bridges the gap between material science and product design by facilitating the iterative process and discussions with all stakeholders in product development.
Scientific realistic simulations of the materials allow R&D engineers to observe the impact of materials’ absorption and diffusion properties in order to find the best elements that meets the specific aesthetic preferences of product designers.
Product Design Iterations: Evaluate material combinations to assess the appearance of the final product:
Ocean™ provides essential tools for the purposes of R&D in jewelry design. To evaluate the final appearance of the product, our simulation software allows product designers and materials engineers to perform rapid in-situ iterations of complex material interactions, adjusting combinations and properties.
The material combination simulations below, generated with Ocean™, illustrate the iterative process made possible by science-based virtual prototyping.
Figure 11: In-situ observation of 3 iterations of material combinations. Simulations generated with Ocean™
Conclusion - Iterative digital prototyping to optimize product design
The appearance of gemstones is difficult to predict due to the complex interplay between their geometry, surface and volume properties, and light.
The Ocean™ workflow has proven to be the key to overcoming the challenges of digital gemstone simulation, providing engineers and designers with a powerful tool to achieve precise control over gemstone aesthetics. Through careful analysis of the gem’s properties and iterative digital prototyping, Ocean™ enables optimization of material decisions, minimization of production costs, and the realization of creative visions.
As the jewelry industry continues to evolve, Ocean™ is an essential tool that empowers professionals to push the boundaries of gemstone design. With its comprehensive capabilities and scientific approach, Ocean™ makes it possible to combine digital simulation and accurate appearance prediction.
All the simulations presented in this article were generated with Ocean™.
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