Several hundred named colors start with G across the major catalogs — Wikipedia's color lists, Crayola's historical crayon catalog, Pantone, RAL, the xkcd Color Survey, and heritage paint references. This page currently lists 104 notable G-color names, deduplicated by hex value. Eight CSS named-color keywords start with G when the gray/grey alias pair is counted separately: gainsboro, ghostwhite, gold, goldenrod, gray, grey (an alias for gray at the same hex), green, and greenyellow. By that counting convention (distinct CSS keywords including spelling aliases), G is well-stocked with CSS named-color keywords compared with most letters.

Several strong candidates. Gold (#FFD700) is one of the most recognizable CSS named colors — a vivid flat digital yellow-gold, fixed by the W3C CSS Color Module specification. (It should not be presented as a physically faithful reproduction of metallic gold, since metallic gold's appearance depends on reflectance, viewing angle, and surface properties that no flat sRGB swatch can reproduce.) Goldenrod (#DAA520) is another CSS-named G-color, named after the Solidago wildflower genus native to North America. Greenery was Pantone's Color of the Year for 2017. Granny Smith Apple is named after Maria Ann Smith, who propagated the original chance seedling at her Eastwood orchard near Sydney in 1868 (per the City of Ryde's historical record). Gainsboro is the pale-gray CSS named color added to the X11 color list in 1989 by Paul Raveling from Sinclair Paints color samples. Gamboge is the historic yellow pigment from Cambodian Garcinia trees.

The W3C CSS named-color list preserves both American (gray) and British (grey) spellings for every named color that contains "gray." Per MDN's authoritative listing, those pairs are gray / grey, darkgray / darkgrey, darkslategray / darkslategrey, dimgray / dimgrey, lightgray / lightgrey, lightslategray / lightslategrey, and slategray / slategrey. Both spellings of each pair resolve to identical hex values. The CSS spec also contains two non-gray alias pairs (aqua/cyan and fuchsia/magenta), for a total of nine alias pairs in the spec. The convention was inherited from the X11 color set defined in 1989 for the X Window System on Unix workstations; the X11 lineage of these names is documented (notably Paul Raveling added extended off-white colors including Gainsboro). The bare gray / grey pair is the base of the seven gray-related pairs and appears on this page.

The CSS named color green is fixed at #008000 — exactly half brightness in the green channel — while the pure RGB green at maximum brightness (#00FF00) is named lime in the CSS spec. The reason is historical. The CSS named-color list inherited its core values from the original 16-color VGA palette used by IBM and Microsoft Windows from the late 1980s, which in turn drew on earlier color text-mode conventions. In the VGA 16-color set, "green" was defined at half brightness so that a brighter "lime green" could exist in the same palette as a separate named color. When the HTML 4 specification standardized the basic 16 color keywords in the late 1990s (later carried into CSS Color Module Level 1), the same half-brightness green was preserved for backward compatibility with millions of existing HTML pages. Authors who want the full-brightness green (#00FF00) should use lime, not green. The same VGA half-brightness convention also produces CSS red #FF0000 vs no half-brightness sibling (so "red" got the maximum slot), blue #0000FF (also the maximum slot), and maroon #800000, navy #000080, olive #808000, purple #800080, teal #008080 (all the half-brightness "color-pair" partners of red/blue/yellow/magenta/cyan respectively).

Gamboge is a deep golden-yellow resin pigment extracted from several species of Garcinia tree native to Cambodia, Thailand, Vietnam, and Sri Lanka — most famously Garcinia hanburyi. The name derives from Camboja, an old European form of "Cambodia" (the East India Company began importing it to Europe around 1615 under this name). The resin is extracted by making spiral incisions in the bark of trees at least ten years old and collecting the resin in hollow bamboo canes (where it solidifies into the characteristic cylindrical "pipe gamboge" form). Gamboge has been used as a yellow pigment in East Asian watercolor and manuscript illumination since at least the 8th century, and is famously associated with the deep saffron-gold color of Theravada Buddhist monks’ robes (its use as the actual fabric dye is debated). Gamboge has a darker side: the resin is acutely toxic — used historically as a powerful cathartic, sometimes fatally — and also has poor lightfastness, so most modern paint manufacturers (Winsor & Newton, Royal Talens, Old Holland) now sell "New Gamboge" — synthetic, non-toxic, lightfast formulations that preserve the historic golden hue. There was a brief supply disruption in the 1970s–80s when shipments from Cambodia were found to contain Khmer-Rouge-era bullet casings and other impurities.

For the CSS-named G-colors (Gainsboro, GhostWhite, Gold, GoldenRod, Gray/Grey, Green, GreenYellow — gray and grey are spelling aliases at the same hex, shown once here), yes — the W3C CSS Color Module specification fixes the exact sRGB values, and every modern browser renders them identically. Note that gray and grey resolve to the same hex value (#808080), and that CSS green (#008000) is half-brightness, not full-saturation (full-saturation green is named lime at #00FF00). For Pantone (Greenery = PANTONE 15-0343, the 2017 Color of the Year), hex values are approximate conversions from Pantone's proprietary swatch books, which are defined under specific lighting conditions. For brand colors (Google Chrome's four-color palette, Giants Orange for the San Francisco Giants), the authoritative reference is each brand's own published guide; this page uses cataloged Wikipedia / public-database values where verifiable.