R Colour — A Diamond Grade in the GIA Very-Light Range
R Colour — A Diamond Grade in the GIA Very-Light Range
The penultimate grade before the colourless-to-light scale gives way to fancy colour at Z
R is a colour grade in the GIA D-to-Z diamond colour scale, falling within the band designated very light (N through R). A diamond graded R shows a noticeable yellow or brown tint visible to the trained grader against a comparison stone, and is in most settings discernible face-up to a careful observer without specialist training. The grade sits one position before S in the descending scale, and four positions above the boundary at which colour ceases to be a defect and is reclassified as fancy colour.
Position in the GIA scale
The GIA D-to-Z scale describes the absence of colour in a near-colourless or yellow-to-brown diamond. D is colourless; the alphabet runs descending through E, F (colourless), G, H, I, J (near-colourless), K, L, M (faint), N through R (very light), and S through Z (light). At Z the conventional scale terminates and any further saturation reclassifies the stone as fancy light yellow or fancy yellow under the separate fancy-colour grading system. The system was developed by Richard Liddicoat and colleagues at GIA in the early 1950s and has been the dominant international standard for diamond colour grading ever since.
R falls in the lower part of the very-light band. A trained grader using master stones in standard daylight-equivalent illumination will identify the R tint as distinctly more saturated than the higher very-light grades, and the colour is generally visible face-up in stones above approximately half a carat. Grading is done table-down against a calibrated set of master diamonds in a colour-neutral viewing environment; the grader compares the unknown stone to the masters and assigns the grade closest in saturation.
Setting and trade context
R-colour diamonds are uncommon in fine jewellery retail. Where they do appear, they are typically set in yellow or rose gold to minimise the perceived contrast between metal and stone — a colourless mounting in white gold or platinum exaggerates the body colour, while warm-toned mountings absorb it visually. The price differential between near-colourless grades and R is significant: a one-carat R-colour stone in commercial qualities trades at a fraction of the price of an equivalent G or H, with the relationship steepening at larger sizes.
The R grade is more commonly encountered in old-cut stones from antique jewellery, where colour was historically less prioritised than cutting quality, than in modern commercial production where lower-colour rough is increasingly steered toward fancy-colour treatment programmes or industrial use. R-colour rough may also be subjected to high-pressure high-temperature (HPHT) treatment to remove brown tint and produce stones grading several positions higher; the treatment is permanent but must be disclosed under standard trade terms.
Distinguishing R from adjacent grades
R is bordered above by Q and below by S. The visual differences between adjacent grades are subtle and not reliably distinguishable by the unaided eye in mounted stones, even for experienced graders working without master comparison stones. For this reason, point-grading — the practice of writing a colour grade as a fractional offset from a letter — is not part of GIA practice; the laboratory issues a single-letter grade and does not differentiate within the band.