Gemstone Clarity & Grading Guide
Understand the diamond 4Cs, coloured gemstone clarity types, and common treatments — with grade-by-grade comparisons.
The 4Cs Work Together
No single "C" determines a diamond's value or beauty in isolation. A large diamond (high carat) with poor cut will look dull and lifeless, while a smaller, well-cut diamond can appear brighter and more valuable. When evaluating a diamond, cut quality has the greatest visual impact on brilliance, followed by colour and clarity, with carat weight being the most straightforward but least important factor for beauty.
Clarity Grades You'll Never See in a Store
Grades like I2 and I3 exist on the GIA scale but are rarely used in fine jewellery — inclusions at this level are visible without magnification and can affect durability. Most jewellery sold at retail falls between VS2 and SI1, offering the best value: inclusions are invisible to the naked eye but the price is meaningfully lower than flawless grades.
Coloured Gemstones Are Graded Differently
Unlike diamonds, coloured gemstones are graded on a Type I, II, III system based on how commonly inclusions occur in that species. Type I stones (aquamarine, tanzanite) are typically eye-clean; Type III stones (emerald, red beryl) are expected to have visible inclusions even in top-quality specimens — an emerald judged by diamond clarity standards would almost always fail, which is why the systems differ.
Why Treatment Disclosure Matters
Most coloured gemstones sold today are treated in some way to enhance colour or clarity — this is standard industry practice, not deception, provided it's disclosed. The concern arises when treatments are undisclosed, as they can significantly affect value, durability, and appropriate care (for example, oiled emeralds should never be cleaned ultrasonically). Reputable dealers always disclose treatments at point of sale.
Working With Casa Jewels
Casa Jewels sources and grades gemstones to the standards your market requires, with full treatment disclosure on every stone. We can also advise on the right clarity/colour combination to hit a specific price point for production runs.
Get in touch →Also see our Diamond Shapes & Size Chart and Gemstone Size & Weight Chart.