GRS Royal Blue is a colour designation issued by GemResearch Swisslab (GRS), the Lucerne-based gemmological laboratory, to sapphires whose colour meets the laboratory's proprietary reference standard for vivid blue with medium-to-medium-dark tone and high saturation. The call appears as a supplementary notation on the GRS report — typically rendered as GRS-type "Royal Blue" — and is among the most commercially significant colour appellations in the sapphire trade, capable of meaningfully influencing hammer prices at auction and private-treaty sales alike.

What the Designation Describes

GRS evaluates colour against a set of physical master stones and standardised colour references developed in-house. A sapphire earning the Royal Blue designation must display a blue of sufficient saturation and depth to align with the historical ideal associated with the finest Kashmir, Burmese, and Ceylonese material — a pure, richly saturated blue free of grey or violet modifiers that would shift the stone toward "cornflower" or "violet-blue" territory. The tone range targeted is broadly medium to medium-dark: stones that are too pale fall toward the GRS-type "Cornflower Blue" designation, while stones that are excessively dark lose the luminosity the market prizes.

The designation is origin-agnostic in principle: GRS applies it to any sapphire meeting the colour threshold regardless of provenance. In practice, however, the stones most frequently receiving the call originate from Kashmir, Burma (Mogok), and Sri Lanka (Ceylon), the three localities whose finest productions historically defined the royal blue standard in the trade.

How It Appears on a GRS Report

GRS laboratory reports are structured to separate origin determination from colour description. The colour designation is appended as a trade-colour remark, phrased in the format GRS-type "Royal Blue" to make clear that the term reflects GRS's proprietary colour reference rather than a universally standardised grade. This convention — placing the laboratory's name before the colour call — was introduced to signal that different laboratories may apply similar-sounding terms using different criteria, and that the GRS call is traceable specifically to GRS's reference system.

Market Significance

Within the international sapphire market, the GRS Royal Blue designation functions as a quality signal that buyers and sellers treat as a meaningful price variable. Fine sapphires accompanied by a GRS report bearing the Royal Blue colour call routinely command premiums over comparable stones graded without such a notation, reflecting collector and investor confidence in the consistency of GRS's colour standards. The designation carries particular weight in Asian auction markets — notably Hong Kong — where GRS reports have historically enjoyed strong acceptance alongside those of Gübelin and SSEF.

It should be noted that the premium attached to any colour designation is ultimately a market convention rather than an intrinsic property of the stone. A sapphire of identical colour assessed by a different laboratory may receive a differently worded description, and buyers sophisticated in gemmology evaluate the physical stone alongside the report rather than relying on the designation alone.

Relationship to Other Blue Colour Calls

GRS employs a family of colour designations for blue sapphires, of which Royal Blue represents the most commercially prestigious tier. The GRS-type "Cornflower Blue" designation describes lighter, more violetish blues — the colour associated with fine Sri Lankan material of a particular character — while stones of very deep tone may simply be described by their colour without a named trade-colour appellation. The distinctions between these calls are consequential in the market: a Cornflower Blue and a Royal Blue sapphire of otherwise equivalent quality can differ substantially in price, reflecting buyer preference for the deeper, more saturated standard.

Laboratory Context

GemResearch Swisslab was founded in 1974 and is headquartered in Lucerne, Switzerland, with additional offices in Bangkok and Hong Kong. It is one of the three major Swiss-based laboratories — alongside Gübelin Gem Lab and SSEF (Swiss Gemmological Institute) — whose reports are widely accepted in the fine-gemstone trade. GRS is particularly noted for its origin-determination work on sapphires and rubies from classic Asian localities, and its colour designation system has been developed in parallel with that origin expertise.