At CG, every diamond is hand-selected, optigonally GIA-certified, and ethically sourced. Whether you're commissioning an heirloom engagement ring or selecting a signature piece, our process begins with transparency and ends with timelessness. If you'd like to learn more or begin a bespoke design, our custom team is here to guide you, stone by stone.
Founded in 1931, the Gemological Institute of America (GIA) is the world’s foremost authority on diamonds, gemstones, and pearls. Created to bring clarity, transparency, and ethical standards to the jewelry industry, GIA pioneered the modern diamond grading system and remains the gold standard in gemological science. As a nonprofit institution, its sole mission is to protect buyers and sellers alike through unbiased, laboratory-based analysis.
In 1953, GIA introduced the 4Cs of Diamond Quality—Cut, Color, Clarity, and Carat Weight—along with the International Diamond Grading System™, which remains the global benchmark today. These criteria brought order to what was once a subjective world, giving clients a shared language to evaluate beauty and value. At Standard Assay, we use GIA grading as the foundation of our curation and bespoke services, ensuring every diamond meets a higher bar: one set by science, shaped by artisanship, and chosen for lasting emotion.

  • The most important of the 4Cs—cut determines how brilliantly a diamond reflects light. Even with perfect clarity and color, a poorly cut diamond can appear dull. GIA grades cut on a scale from Excellent to Poor. We seek only exceptional craftsmanship that balances fire, brilliance, and symmetry—because sparkle is science.

  • Diamonds are graded on a scale from D (colorless) to Z (light yellow or brown). The less color, the rarer the stone. Most of our fine diamonds range from D–G for their crisp, luminous appearance, often set in metals that complement their icy or warm undertones.

  • This measures the purity of the diamond and the presence of internal (inclusions) or external (blemishes). Ranging from Flawless (FL) to Included (I1–I3), clarity can impact both brilliance and value. Many of our curated pieces are in the VS–VVS range—meaning they're virtually eye-clean but still carry the magic of nature's fingerprint.

  • More than just size, carat reflects a diamond’s physical weight, with 1 carat equaling 0.2 grams. But remember: a well-cut 1.00 carat can look more radiant than a heavier poorly-cut stone. We work closely with our clients to find the ideal balance between presence and proportion.