Historically, colours associated with royalty and high status were almost always the colours that were hardest and most expensive to produce reliably — the association was fundamentally economic before it became purely symbolic.
Tyrian purple's restriction to Roman and Byzantine imperial rank is one of the best-documented examples of a colour's cost directly determining its legal and social restriction.
Clothing and status · Rome and Byzantium
Sumptuary laws — legal restrictions on who could wear which colours and fabrics — existed in various forms across medieval and early modern Europe and parts of Asia, generally reserving the most costly dyed and richly coloured cloth for the highest social ranks.
Clothing and status · Europe and parts of Asia · medieval to early modern period
Once synthetic dyes made formerly rare colours widely affordable from the mid-19th century onward, many of these older status associations weakened, even though some (such as purple's link to royalty) persisted culturally long after the economic reason had disappeared.
Changing meaning · 19th century onward
Historical claims above are scoped to a specific period, region or culture where relevant — none are presented as a single universal fact. See methodology.