Diamond cutting is the process of transforming a rough diamond into a faceted polished diamond.

The main goal of this process is to reach the biggest yield to maximise the value of the finished diamond. Besides retaining the most of the weight, diamond cutters will strive to achieve the excellent proportions, symmetry and polish. When done right, it will lead to a diamond having a distinguished Hearts and Arrows pattern in and a lot of fire, brilliance and scintillation. The rough crystal will change many hands and go through a number of different countries and cultures in order to achieve this desired goal.

This timeline is a simplified overview. The specific stages and techniques used may vary depending on the individual diamond and desired outcome.

Author: Alex K., CMO at Labrilliante Updated: 2025-10-12 Reading Time: 8 minutes

Many established jewelers argue that investing in specialized lab diamond cutting equipment and training isn't worth the cost. They point to the significant upfront investment in new technology, staff retraining, and certification processes when traditional cutting methods have served the industry for decades. Some professionals believe the market hasn't matured enough to justify switching from proven natural diamond techniques.

These concerns hold merit for smaller operations with limited capital or established customer bases focused on natural stones. Traditional cutters working exclusively with natural diamonds may find their existing skills and equipment sufficient for their market segment. However, this viewpoint overlooks the growing consumer demand for lab diamonds and the superior yield rates achievable with specialized techniques. The controlled nature of lab diamond production actually makes them more predictable to cut than natural stones, offering better returns once proper methods are implemented.

Transforming rough lab diamonds into polished gems involves three key stages: assessment, blocking, and precision cutting. Each stone requires 4-8 hours of skilled work, depending on size and complexity.

Blocking shapes rough crystals into basic geometric forms called cuboctahedrons. This intermediate stage features eight triangular faces that provide optimal surface area for subsequent operations.

During blocking, cutters use controlled cleaving to remove unwanted portions while preserving maximum weight. Incorrect cleaving destroys the entire stone. CVD diamonds require modified approaches due to their layered structure, while HPHT stones cleave more predictably.

The process considers final proportions, ensuring proper depth percentages and girdle thickness for the intended cut. Growth-related imperfections specific to each diamond type get addressed during this critical phase.

A standard one-carat round brilliant requires 6-12 hours across all stages. Fancy shapes demand 15-20 hours due to increased complexity and precision requirements.

Modern facilities achieve 40-60% yield rates from rough to polished, balancing weight retention with quality targets. Each stage undergoes symmetry checks to maintain alignment and proportion relationships.

Quality control inspections at multiple points prevent costly defects before they become permanent. This approach ensures efficient resource use while maintaining consistent output quality.

CVD and HPHT diamonds demand different cutting approaches due to their distinct formation methods and resulting crystal characteristics. Understanding these differences is crucial for optimal results.

Directional hardness presents the biggest challenge in lab diamond cutting, especially for CVD stones. While all diamonds rate 10 on the Mohs scale, actual hardness varies by crystal direction and growth method.

CVD diamonds show pronounced hardness differences between growth layers, requiring adaptive cutting techniques. Cutters adjust speed, pressure, and angles continuously, monitoring for surface finish consistency throughout the process.

Solutions include specialized scaife wheel configurations for each growth type, different diamond powder compounds, and real-time monitoring systems that automatically adjust parameters as conditions change during cutting operations.

These three primary stages serve distinct purposes in diamond transformation. Cleaving removes unwanted portions, bruting creates basic round shapes, and brillianteering adds precision facets determining optical performance.

Lab diamond cleaving requires understanding growth-induced stress patterns. CVD stones may exhibit unexpected behavior due to layering, while HPHT stones cleave more predictably due to uniform formation under controlled pressure.

Brillianteering consumes 60-70% of total cutting time, involving precision faceting with diamond powder on rotating wheels. This stage determines final symmetry, alignment, and surface finish quality that directly impacts certification grades.

IGI and GIA use different methodologies for cut quality evaluation, creating variations in measurement criteria, standards, and reporting that affect market perception and pricing.

IGI focuses on comprehensive technical analysis with detailed precision metrics including symmetry assessment, proportion relationships, and optical performance data. Their reports provide extensive technical information appealing to professional buyers seeking detailed quality documentation.

GIA emphasizes standardized grading aligned with established protocols, prioritizing consumer clarity and market consistency over technical detail. Their approach makes reports more accessible to general consumers while maintaining rigorous standards.

Both organizations evaluate identical physical characteristics but present findings differently. Professional markets often prefer IGI's technical detail, while consumer segments may favor GIA's brand recognition and simplified communication.

Certification choice impacts pricing, with different regions showing preferences for specific organizations. Processing timelines vary, with IGI typically providing faster turnaround while maintaining comparable accuracy standards.

Superior cutting directly influences value through light performance optimization, certification grades, and market perception. Excellent cut quality commands 15-25% premiums over good grades in comparable stones.

Poor cutting severely impacts value, with symmetry or proportion defects reducing market worth by 30-50% compared to well-cut alternatives. These defects cannot be corrected post-cutting, making initial quality decisions critically important.

Each cut grade improvement typically generates 8-12% value increases, providing clear economic justification for precision techniques. However, cutting investment must balance maximum weight retention against optimal proportions, as poorly proportioned diamonds suffer significant discounts regardless of carat preservation.

Wholesale pricing shows direct correlation between certification grades and market value. The controlled nature of lab diamond production enables more consistent cutting quality achievement, potentially stabilizing value relationships compared to natural diamond variability.

Investment considerations include market acceptance trends, certification consistency, and long-term stability factors that may differ from natural diamond patterns. Professional buyers consistently demonstrate willingness to pay substantial premiums for documented cutting excellence.