Lotus Royal Blue is the Lotus Gemology laboratory's defined colour grade for sapphire that meets the parameters of the historic royal blue description: a vivid, medium-strongly saturated blue of medium tone, with a slight violet bias, free of green or grey modifiers, and reading as a clean blue across daylight and tungsten illumination. The designation is granted only when a stone matches Lotus's published reference window and is independent of origin and treatment status.

Structured tiers

The Lotus royal blue call is broken into three tiers - RB1, RB2 and RB3 - covering the apex, the middle and the entry point of the category respectively. The structured scale parallels the Lotus pigeon blood scale for ruby and serves the same purpose: limiting dilution of the royal blue term and giving the trade vocabulary for distinguishing among royal blue stones.

Trade significance

A Lotus royal blue call is one of three or four sapphire colour designations that materially move price on a top-grade stone, alongside the Gübelin and SSEF royal blue calls. The highest-priced sapphires in the market typically carry royal blue designations from more than one laboratory, an unheated heat-treatment status, and a top-tier origin determination such as Kashmir or Mogok.