Colour Chip Set
Colour Chip Set
Portable resin references for rapid colour communication in the coloured-stone trade
A colour chip set is a series of standardised plastic or resin wafers, each representing a specific combination of hue, tone, and saturation, used by gem dealers, sorters, and buyers as portable visual references when grading or communicating the colour of coloured gemstones. Unlike master-stone sets — which employ actual cut gemstones of agreed colour — colour chips are manufactured from pigmented synthetic material, making them far more affordable, durable, and easy to carry into the field or across a trading floor. Their principal value lies in speed and convenience: a dealer sorting a parcel of sapphires or rubies can hold a chip against each stone and assign a shorthand colour code in seconds, enabling consistent internal communication without the logistical burden of transporting fragile, high-value master stones.
Construction and Coverage
Chips are typically moulded from acrylic or resin and finished to a consistent thickness and surface texture intended to approximate the face-up appearance of a faceted stone under standardised lighting. A complete set generally spans the visible spectrum in incremental steps of hue (red, orange, yellow, green, blue, violet, and their intermediates), with multiple chips per hue representing graduated tones from light to dark and saturations from weak to vivid. Some suppliers issue separate sub-sets focused on commercially important colour ranges — sapphire blues, ruby and spinel reds, emerald greens — with finer gradations within those windows where market distinctions carry the greatest price consequence.
The chips are typically mounted in a ring binder, a fan-deck format, or individual sleeves, and are labelled with alphanumeric codes that dealers can record on parcel papers or invoices. A notation such as B5 or R3T4 (hue-saturation-tone shorthand varies by supplier) allows a buyer in Bangkok to communicate a colour target to a cutter in Jaipur without shipping a physical reference stone.
Limitations and Calibration
The central limitation of colour chip sets is the absence of universal calibration across the trade. Each manufacturer produces chips to its own internal standard, and there is no internationally ratified system — analogous to the Pantone system in printing — that all gemstone suppliers have adopted. A chip coded Blue 6 from one supplier may not correspond precisely to Blue 6 from another. This means that colour-chip codes are reliable only within a single trading relationship or company where both parties use the same set from the same production run; they cannot be cited in laboratory reports or auction catalogue descriptions as objective colour designations.
A further complication is metamerism: the pigments used in resin chips may match a gemstone's appearance under one light source (commonly a daylight-equivalent fluorescent tube) but diverge noticeably under incandescent or LED illumination. Gemstones, particularly those with complex absorption spectra such as alexandrite or colour-change garnet, will shift in appearance across light sources in ways that a static chip cannot replicate. For this reason, chip-based grading is generally considered a first-pass sorting tool rather than a definitive colour assessment.
Physical degradation is also a practical concern. Resin chips are susceptible to fading and surface scratching over time, meaning that a set used heavily over several years may no longer match the manufacturer's original standard. Reputable suppliers recommend periodic replacement of working sets.
Relationship to Master-Stone Sets
Master-stone sets — assemblages of actual gemstones selected and agreed upon as colour benchmarks — remain the most precise reference tool available to the trade. The GIA colour-grading system for coloured stones, and the colour-communication frameworks used by major laboratories such as Gübelin and SSEF, are ultimately anchored in spectrophotometric measurement and trained human observation rather than chip comparison. Colour chips occupy a complementary, lower tier: they are the working tool of the wholesale floor, the buying trip, and the sorting room, while master stones and instrumental measurement serve the higher-stakes functions of laboratory grading and significant auction or retail transactions.
Use in the Trade
Colour chip sets are most widely employed in the major wholesale trading centres — Bangkok's Silom Road gem district, the Jaipur cutting and trading hub, and the Colombo and Ratnapura markets of Sri Lanka — where large volumes of stones change hands rapidly and a shared visual shorthand accelerates negotiation. Many established trading houses maintain their own proprietary sets that have been calibrated against a house master-stone collection, effectively creating an internal colour language that is consistent across their buying offices in multiple countries. Newer entrants to the trade often begin with commercially available sets from suppliers such as the American Gem Trade Association (AGTA) or specialist gemmological suppliers, before developing house standards as their operations mature.
In summary, the colour chip set is a pragmatic, widely used instrument of commercial gemmology — valuable for its portability and speed, but best understood as a communication aid rather than a precision grading tool.