[3][4][5][6] The preparation of ROY was first disclosed in a series of patents from Eli Lilly & Co. in the 1990s, which covered the pharmaceutical active ingredient later marketed as olanzapine.

When this ability to form multiple crystalline versions of different colours was reviewed in 2010, it was described as "extraordinary", particularly because many alternatives can crystallise simultaneously from a single solvent.

[4] By 2020, ROY held the record for having the largest number of well-characterised polymorphs, with its nearest competitors being aripiprazole and galunisertib.

[9][10][11] The various crystal forms display alternative conformers, a type of stereoisomerism where rotation at single bonds leads to a distinct three-dimensional configuration in the solid.

[12] The molecule is piezochromic, with yellow and pale orange crystalline forms which transform reversibly to red at high pressure.