GSL provides authoritative diamond certification through meticulous clinical analysis and unbiased gemological expertise.
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Accuracy is not an aspiration; it is a mandate. In the landscape of high-value assets, GSL serves as the objective observer.
We operate beyond the fluctuations of the market. Our laboratory leverages precision instrumentation and deep gemological knowledge to ensure every certificate issued is a definitive record of truth, fostering absolute confidence for both the industry and the consumer.
Detailed analysis of the 4Cs (Carat, Cut, Color, Clarity) using rigorous laboratory protocols to determine precise quality benchmarks.
Comprehensive valuation services for finished jewelry items, ensuring insurance and market documentation meets institutional standards.
Expert advisory for high-value gemstone acquisitions and portfolio management through a scientific lens.
The GSL Report is the industry standard for unbiased stone assessment, recognized globally for its uncompromising accuracy.
Request SampleIn an industry built on rarity, trust is the rarest commodity of all. GSL provides the empirical foundation upon which that trust is built.Laboratory Principles, GSL
Our laboratories in New York and global hubs operate Monday through Friday, 9:00 AM – 5:00 PM. Please initiate your consultation or submission below.
Mon — Fri: 9:00 AM - 5:00 PM
Sat — Sun: Closed
Unbiased. Reliable. Accurate.
Diamond Grading (4Cs)
Gemstone Analysis